Preliminary Design of Tunnel

CHAPTER 9
PRELIMINARY DESIGN OF TUNNEL

CHAPTER 9
PRELIMINARY DESIGN OF TUNNEL
9.1 GEOLOGICAL CONDITION
9.1.1 Geological Survey

In order to confirm the geological condition of Nagdhunga tunnel, following investigations has
been carried out.
· Geological survey
· Aerial photo interpretation
· Electrical Resistivity Tomography
· Seismic prospecting exploration (Changed into Microtremor Array Measurement)
· Drilling survey
FIGURE 9.1-1 LOCATION MAP OF GEOLOGICAL SURVEY
TABLE 9.1-1 SURVEYED AMOUNT LIST
1) Geological survey was carried out in the range of 12km2 around the tunnel planned route.
2) The geology of the study area consists of interbedded sandstone and phyllite of the
Paleozoic, where many cracks develop as well as thinly developed bedding planes.
9-1
3) Survey results are shown in Figure 9.1-2.
4) Aerial photo interpretation was carried out by stereoscopic interpretation with scale of 1:
50,000, using the black-and-white photo, taken on 1 November 1992. Results have been
reflected on the geological mapping and surface geological survey results.
5) Electrical Resistivity Tomography prospecting has been done along the planned survey
lines which cross the original tunnel alignment. And because the seismic prospecting
exploration along the tunnel alignment could not be carried out due to the difficulty to
obtain permission, ERT was additionally carried out along the tunnel longitudinal
alignment. It should be noted that DOR had carried out several surveys for the feasibility
study in the vicinity of the project tunnel (in Feb. 2013) and the results of this study are also
reflected in the report. The survey results are shown in Figure 9.1-3.
6) Seismic refraction exploration was planned to be carried out along the tunnel alignment but
because of the availability of dynamite required by the survey was difficult, it was changed
to Microtremor Array Measurement (MAM). The survey results are shown in Figure 9.1-4.
7) Boring survey was conducted in order to confirm the depth and the properties of the
bedrock in the valley areas which cross the tunnel alignment. The boring results obtained
are reflected in the photos in Figure 9.1-5.
FIGURE 9.1-2 GEOLOGICAL MAP OF SURVEYED AREA
9-2
9-3
FIGURE 9.1-3 INTERPRETED RESULTS OF ERT
9-4
FIGURE 9.1-4 INTERPRETED RESULTS OF MAM
FIGURE 9.1-5 BORING CORES PHOTOS
9-5
Soft Soil
Weathered rock
Fresh rock
FIGURE 9.1-6 INTERPRETATION OF RESULTS OF MAM, ERT AND BORING
9.1.2 Summary of geological survey on Nagdhunga Tunnel

· The Nagdhunga tunnel is mostly planned in the direction of east and west, starting from
Basnetchhap as eastern portal and passes under the Sisne khola to Nagdhunga pass and
reaches to the west side portal, and is 2450 m long.
· The geology of this section is Sopyang formation of Paleozoic era.
· Sopyang formation is the thin alternation of sandstones and phyllites.
· The thickness of each sand stone layer is 5 to 30 cm and phyllites are 1 to 5 cm thick, and
many cracks develop due to repeated small foldings.
· There are three wide valleys along the tunnel alignment.
· These valleys are filled up with the sediment of talus and clays which deposited when
Katmandu basin had been a lake.
· The thickness of the sediments are 20 to 40 m.
· The weathering layer of bedrock is 30 to 40 m from the surface, and below the weathered
rock fresh and hard rock with fractures are confirmed by boring.
9-6
· Although the groundwater level is assumed to be about 30-40m from surface in a mountain
part, about 5-10m from surface are confirmed in the valley area.
· In the west side portal area a little weathered alternations of sandstone and phyllite are
exposed, Relationship of excavation slope and bedding planes of the strata shows that
slopes to be cut are rather stable because the strata dip into the slope.
· In the east side portal, talus sedimentary layers are thick, and also cohesive soil is
distributed over the lower part of a talus cone.
· Longitudinal geological profile is shown in the attached drawing sheets.
FIGURE 9.1-7 FEATURES OF BEDROCK WITH MANY CRACK
9.2 KEY POINTS FOR TUNNELING FROM THE VIEWPOINTS OF GEOTECHNICAL

CONDITION
Issues particularly important for the implementation of Nagdhunga Tunnel are summarized as
follows;
· It is of great importance in designing the tunnel support pattern and method of tunneling of
Nagdhunga Tunnel to maintain the groundwater level as much as possible to the present
level, where habitants are using surface water flow and groundwater, and houses near
eastern portal shall be maintained safely during tunneling. When shortage of water is
triggered it will induce serious difficulty in the implementation of the project.
· Slopes surrounding tunnel portals shall be maintained stable permanently and stream waters
shall be adequately managed not to harm the tunnel.
· In the planning of tunneling method it must be reflected that there distributes to some extent
hard massive sandstones which may be very difficult for mechanical excavation method
without using heavy breaker or some other auxiliary method.
· Another point of importance is that tunneling method and support design shall be adequate
to cope with fault zones to be encountered during tunneling although the exact location and
nature of the fault zones are not identified yet.
All of the above issues are to be reflected in the design of tunnel support and method of
excavation for Nagdhunga Tunnel.
Necessary auxiliary methods and measures and their cost thereof are considered in the design,
method of tunneling and cost analysis.
9-7
9.3 ENGINEERING APPROACH
9.3.1 Design Standards

There is no design standard for tunnels included in the Nepal Standards. All design standards
for road tunnels in developed countries are quite similar.
Japan is the one of the most experienced countries in tunneling in the world, and as the geology
and geotechnical condition of Japan is very similar to that of Nepal, the present study for
tunneling for the Nagdhunga Pass Project is based upon the experiences in Japan and the design
of the tunnel is based on the Standard of NEXCO (Nippon Expressway Company, former Japan
Highway Corporation), which is applied to all the highway tunnels and most of national road
tunnels in Japan, most of which have been constructed by NATM. Because NATM is applied
for most of the tunnels worldwide Nagdhunga Tunnel is to be constructed by NATM.
NATM is first established in Austria, which utilizes shotcrete and rockbolts as major supporting
system generally in hard rock mass with measurement of deformation of tunnel walls to
evaluate whether the tunnel is stable or not. And if not, additional support measures are applied
accordingly.
However, Japanese contractors have applied the method generally in very poor ground and
during constructing so many tunnels in difficult ground, Japanese contractors have advanced
the method by themselves and innovated various kinds of auxiliary methods and specific
equipment for supporting the poor ground.
Result of Data Collection Survey shows that the proposed width of the road in tunnel is 2 x
3.5m lanes with 2.5m wide lane for emergency parking at east bound direction and 0.5m wide
shoulders on both sides; a walk way for maintenance of the facilities, 75cm wide and 2.0m
high, is required at one side.
No side walk is designed because for the safety of the traffic; non-motorized traffic, such as
pedestrians, bicycles, hand cart and animal traction carts, or agricultural tractors are not allowed
to enter the tunnel. Thus, the total width of the tunnel is about 12 m and the height is about 7 m.
Tunnel design shall follow the above dimensions and clearance in height for the traffic is
determined as 5.0m which is the standard for Asian Highways.
9.3.2 Rock classification method and Standard Support Patterns of the tunnel
(1) Rock classification system and standard support patterns in Japan
Table 9.3.2-1 shows the rock mass classification system of NEXCO and Table 9.3.2-2 shows
the standard support pattern for two lane tunnel.
TABLE 9.3-1 ROCK MASS CLASSIFICATION SYSTEM (NEXCO)
Rock
Condition of rock mass RQD Stability of face convergence
class
B Rock is fresh and hard. 60 to The strength is significantly higher Convergence of tunnels is
Discontinuous planes are 90 than the expected load and only negligible.
stable and the possibility of occasional local spalling of rock
loosening due to tunnel fragment may occur.
excavation is very small.
CⅠ Rock is partly weathered or 20 to The strength is higher than the Convergence of tunnels is usually
altered. Discontinuous 70 expected load and the loosening is within the elastic range.
planes are generally expected to be local.
relatively stable
CⅡ Rock is partly weathered or 20 to Strength is not significantly higher Convergence stops to increase
altered and fractured. 70 than the expected load, but is before the tunnel face has
sufficient to limit the elastic advanced a distance of 2 D, where
deformation. Rock chunks along D is the tunnel diameter.
slippery discontinuous planes tend Convergence of tunnels does not
to spall. Often requires fore-polling. exceed 50 mm.
9-8
Rock
Condition of rock mass RQD Stability of face convergence
class
DⅠ Rock is significantly < 20 Partial plastic displacement and Where the strength is small and the
weathered and softened or elastic deformation could occur. Or invert concrete is not placed at an
sheared. even if the strength is high enough early stage, the convergence could
to limit the elastic deformation, reach 30 to 60 mm and does not
significant loosening of ground stop to increase even if the tunnel
along slippery discontinuous planes face has advanced more than 2 D
could occur. Requires fore-pilings.
DⅡ Rock is completely < 20 The strength is low compared to the Convergence of tunnels could
weathered and partly expected load and large plastic reach as large as 60 to 200 mm and
softened to soil, or heavily deformation as well as elastic does not stop to increase even if
sheared. Talus deposits and displacement could occur. In the tunnel face has advanced more
soil are included in this addition to the low strength, than 2 D, if the invert concrete is
class. significant loosening of ground not placed at an early stage
along slippery discontinuous planes
and large displacement could occur.
E Ground such as faults, Squeezing occurs and generates Large deformation could reach to
fractured zones and large occasional collapse in face area. 400mm.
talus deposit.
TABLE 9.3-2 STANDARD SUPPORT PATTERNS FOR TWO-LANES TRAFFIC TUNNELS

NEXCO
Lining
Rock bolts Shotcrete Steel rib
thickness (cm)
Cut
per Allowable Excava-
Ground Support
class pattern
adva Spacing deformation tion
nce Length Construc- Thickness Upper Lower Arch & (cm) method
(m) Invert
(m) Periph- Longitu- tion range (cm) half size half size wall
eral dinal
(m) (m)
Upper
B B-a 2.0 3.0 1.5 2.0 5 - - 30 0 0
half 120°
Upper
CI C I-a 1.5 3.0 1.5 1.5 10 - - 30 (40) 0
half
C II-a 1.5 1.2 Upper - - Full

and face
C II 1.2 3.0 10 30 (40) 0
lower with
C II-b 1.5 1.2 halves H125 - micro
bench
D I-a 1.0 3.0 Upper or top
and heading
DI 1.2 1.0 15 H125 H125 30 45 0
lower cut
D I-b 1.0 4.0 halves
Upper
1.0
1.0 or and
D II D II-a or 4.0 1.2 20 H150 H150 30 50 10
less lower
less
halves
The support patterns are divided into a and b as shown below.
a: Standard support pattern generally used for all rock types
b: Support pattern used in the initial design only when the tunnel excavation is expected to result in a larger displacement
in clay stone, black schist, mudstone, shale, tuff, or other rock types.
Note that the values in ( ) for the invert are applied to tertiary mudstone, tuff, serpentinite, and other ground rocks,
weathered crystalline schist, and sulfuric soil.
9.4 CROSS SECTION AND SUPPORT PATTERNS OF THE TUNNEL
9.4.1 Tunnel cross section

Cross section of the tunnel is so designed as to meet the requirement to provide two 3.5m wide
lanes and one 2.5m wide lane for emergency parking in the east bound direction. Height of the
construction gauge for the traffic is 5.0m.
9-9
After walk out survey and examining the geological condition on various outcrops, tunnel types
and support designs are preliminarily determined. Then after getting information on
geotechnical and hydrological condition through field investigations, support patterns (and
Tunnel types) and length of distribution of each pattern is defined finally and is reflected in the
longitudinal tunnel profile.
Tunnel types are classified into 3 types in this study to reflect the geotechnical condition of the
tunnel so far encountered and are classified as CⅡ, DⅠ and DⅡ. Cross sections of each tunnel
type are shown in the Sheets NO. 10 to 12 of the Preliminary Design Drawings.
Type CⅡ is to be applied to the ground where rock mass is significantly fractured or sheared.
The type of rock is the alternation of thin slate and sandstone. This type of ground is expected
to develop in the area beneath the ridges and near western portal area and is supposed to share
about 60% of the total tunnel length.
Type DⅠis to be applied to the ground where rock mass is heavily sheared or weathered or to
the CⅡ ground where valley deposits distribute over the rock mass in thin coverage. This type
of ground is supposed to be encountered under the valley at two locations, at Thosne Khola and
west of it, beneath the small ridge at Chisapani where existence of fault zone is anticipated and
in the near portal area where overburden is small. This type of ground is supposed to be of
about 35% of the total tunnel length.
Type DⅡis to be applied to the ground where rock mass is totally weathered and overburden is
very small as in the area of both portals. This may occupy about 5% of the total tunnel length.
It is a general requirement for the tunnel to provide emergency parking areas when the tunnel is
very long. As for the Nagdhunga Tunnel there is a emergency parking lane in the east bound
direction. However, in the west bound direction emergency parking zones shall be provided. In
this study 2 numbers of emergency parking zones are designed at about 800m apart and is
named Type CⅡ-L.
9.4.2 SUPPORT PATTERNS (See Sheets NO. 13 to 16 of the Preliminary Design Drawings)
Referring to the standard support pattern in Table 9.4-1, support patterns for the Nagdhunga
Tunnel are designed.
· Support Pattern CⅡ corresponds to Tunnel Type CⅡ. It consists of 10cm thick shotcrete,
3m long rockbolts at spacing 1.5m peripherally and 1.2m longitudinally. Secondary
concrete lining is 30cm thick. Due to the fractured nature of the rock mass shotcreting for
the excavated face area is sometimes required.
· Support Pattern DⅠ is applied to tunnel class DⅠ. It consists of 15cm thick shotcrete, 3m
long rockbolts at spacing 1.2m peripherally and 1.0m longitudinally. Thickness of lining
concrete is 30cm. The Pattern requires face shotcrete 3 to 5cm thick to stabilize the
excavated face.
· When the rock mass in the invert is very weak and is likely to be deteriorated the support
requires extra H-shaped steel arch (H125) and 45cm thick invert concrete and is named
Support Pattern DⅠ-a. Pattern DⅠ-a requires also an auxiliary method such as fore-poling
and face shotcrete.
· Depending on the rate of ingress of groundwater under the valley area, chemical injection
with long span fore-piling may be required instead of fore-poling to maintain the
groundwater level. When tunneling encounters fault zones same measures may be required.
This support pattern is named as Pattern DⅠ-b.
· Support Pattern DⅡ corresponds to tunnel Type DⅡ. It consists of 20cm thick shotcrete
and rockbolts of 4m long at spacing 1.2m peripherally and 0.75m to 1.0m longitudinally
depending on the stability of the excavated face. It requires steel arch sets of 150H for the
9-10
temporary support of the weight of the above ground. Fore-poling by 3m long rockbolts are
generally required. Secondary lining concrete is 35cm thick in arch and 50cm thick in
invert.
· In eastern portal area the support pattern requires heavy auxiliary method such as long span
fore-piling with chemical injection to maintain the groundwater level (this support pattern is
named Support Pattern DⅡ-a). On the contrary, in the western portal area portal slope is to
be widely cut and fractured but fresh rock mass of CⅡclass is expected to appear in a short
distance from the portal.
· For the portal zones lining concrete shall be steel-reinforced in order to sustain the non-
uniform overburden loads acting on it permanently.
· Western tunnel entrance is to be of reinforced concrete structure of 80cm thick and eastern
tunnel entrance will be more rigid structure to cope with the ground pressure acting on it.
As for the emergency parking zones with which the cross sectional area is very large, the
parking zones shall be designed in Detail Design stage to locate them in the area of better
geotechnical condition.
Table 9.4-1 shows a list of support patterns.
TABLE 9.4-1 LIST OF SUPPORT PATTERNS
Applicable
Support Excavation Advance Excavation Auxiliary Rock Shotcrete Steel- Lining
geological
Pattern area m2 per cycle method method bolt thickness rib thickness
condition
CⅡ 89.16 1.2m Thinly Micro bench 3m 10cm 30cm
bedded mechanical long,
fractured 1.5m(p)
rock mass ,
Alt. of 1.2m(l),
Sst&shale
DⅠ 91.26 1.0m Highly Ditto 3m 15cm 30cm
fractured long,
and 1.2m(p)
weathered ,1.0m(l)
rock mass
(+ Fault
zone)
DⅠ-a 101.97 1.0m Heavily Ditto Fore- Same 15cm 125H 30cm(arch)
fractured, poling 3m as 45cm(inv.)
weathered long above
rock
DⅠ-b 101.97 1.0m Ditto with Ditto Fore-piling Same 15c 125H 30cm(arch)
groundwat (12m) with as 45cm(inv.)
er (under chemical above
the valleys) injection
DⅡ 105.06 0.75- Highly Ditto Fore- 4m 20cm 150H 35cm(arch)
1.0m weathered poling 3m long, 50cm(inv.)
rock mass long 1.2m(p) Steel
with thin 0.75- reinforced
rock cover 1.0m(l)
DⅡ-a 105.06 0.75- Ditto with Ditto Fore-piling Same 20cm 150H 35cm(arch)
1.0m groundwat (12m) with as 50cm(inv.)
er (eastern chemical above Steel
portal area) injection reinforced
Note: (p) means peripheral, (l) means longitudinal
9-11
Important notice on water proofing by chemical injection
In the design chemical injection is intended to be used with AGF in tunnel in order to minimize the
lowering of groundwater level. However, our intention is not to make the tunnel perfectly watertight
but to reduce the water inflow into the tunnel. Thus tunnel is not designed as watertight tunnel.
When geological structure is taken into consideration, that the strike of the strata is generally sub-
parallel to the tunnel axis and dip of the strata is considerably high to the north or to the south due to
occasional folding and that permeability of the rock mass across the bedding planes in thin
alternation of slates and sandstones is generally low because slates are impermeable and sandstones
are permeable and groundwater passes in the fissures of sandstone layers, area of the chemical
injection to be carried out with AGF may possibly be limited to along the arch periphery of the tunnel.
This shall be further studied in detailed design study.
During tunneling whenever groundwater inflows from the excavated side walls through shotcrete
chemical injection shall be done to reduce the rate of inflow.
Groundwater inflow from the face area if any can be accepted because groundwater comes from far
front of the face and when tunnel periphery is closed all the way after the completion of tunneling
groundwater cannot enter into the tunnel and groundwater level may recover gradually.
9.4.3 Longitudinal profile of the tunnel

Longitudinal profile of the tunnel including geotechnical condition and distribution of type of
support are shown in the Sheet NO. 9 of the Preliminary Design Drawings.
9.5 METHOD OF TUNNELING
9.5.1 Geology, geotechnical and hydrological condition of the tunnel

(1) Geology and geotechnical condition
Tunnel ground to be excavated mainly consists of thin alternation of sandstone and shale. Their
geotechnical condition seems to be of poor nature and are classified into CⅡ, DⅠand DⅡ. To
some extent it is anticipated that considerably thick hard sandstones occasionally appear in the
excavation face area beneath the ridge areas and in the selection of tunneling method it is taken
into account. Because the bedding planes of the strata are sub-parallel to the tunnel axis cares
shall be taken to the stability of excavated side walls.
(2) Hydrological condition
With regard to hydrological condition of the tunnel ground, groundwater may infiltrate into the
tunnel where rock mass is sheared or near the portal area and under the Thosne Khola where
tunnel is covered by basement rock with thin cover and water-bearing unconsolidated
sediments develop above the basement rock.
Surface water flows and groundwater are widely utilized in the eastern portal and valley areas
not only for agricultural use but also for domestic use and decrease in groundwater level due to
tunneling may induce serious problem. Necessary measures are designed to preserve the
groundwater level as much as possible in this study.
9.5.2 Excavation method of tunneling
(1) Method of tunneling
There are two methods of tunneling, Drill & Blasting and mechanical excavation. Drill &
Blasting method is generally applied in hard rock mass and when the rock mass is fractured
significant overbreaks occur and heavier support is required compared to mechanical
excavation.
Geology of the Nagdhunga Tunnel consists mainly of thin bedded alternation of shale and
sandstone with many cracks in it and is generally classified as poor rock mass. Thus, the tunnel
shall be excavated mechanically by Road-Header (see Figure 9.5-1 and TABLE 9.5-2).
9-12
· Mechanical excavation has a great merit when it comes to excavate soft rock or hard rock of
poor nature where many planes of discontinuities develop. Overbreaks are much smaller,
support patterns are lighter and the rock mass surrounding the tunnel remains more intact
after excavation than D&B. However, when the rock mass is hard and intact it cannot
excavate the rock mass economically. In Nagdhunga Tunnel occasionally road-header may
encounter hard massive sandstone and utilization of giant breaker may be required in such a
case.
FIGURE 9.5-1 ROAD-HEADER AS TUNNELING MACHINE
TABLE 9.5-1 COMPARISON OF EXCAVATION METHOD

Tunneling Method Drill & Blasting Mechanical
Ø This method is generally applied in hard rock Ø This method is generally applied in middle
mass and soft rock mass. hard rock mass, soft rock mass and sand/soil
Ø In order to use explosives, it is necessary to layer.
exercise caution in the application of this Ø Noise and vibration generated by tunnel
Features method. excavation is small.
Ø Noises and vibrations generated by blasting Ø Overbreaks and loose of ground is small.
method is not small.
Ø Overbreaks is large and ground is likely to be
loose.
Ø Geology of Nagdhunga Tunnel is Ø Geology of Nagdhunga Tunnel is
mainly of thin bedded alternation of mainly of thin bedded alternation of
shale and sandstone with many cracks, shale and sandstone with many cracks,
Applicability and it is possible to apply Drill & △ and it is possible to apply Mechanical ○
Blasting method. But excessive method. It is possible to excavate
overbreaks and loose of ground will be effectively because loose of ground and
Evaluation occurred. overbreaks are small.
Indexes Ø It is necessary to consider the Ø Noises and vibrations generated by
countermeasures of noises and tunnel excavation is small.
Environmental △ ○
vibrations reduction for residents
around west tunnel portal.
Ø Safety measures for application of Ø Necessity safety measures for
Safety explosives are needed. △ Mechanical method are less than that for ○
Drill & Blasting method.
Total Evaluation △ ○
9-13
(2) Excavation method
Tunnel excavation method is classified as shown in エラー! 参照元が見つかりません。.
Depending upon the geotechnical condition excavation face area is sometimes divided into
sections and when geotechnical condition is of extremely poor center diaphragm method or side
drift method are employed. However, geotechnical condition of the Nagdhunga Tunnel is
deemed to be of poor nature, not extremely poor, and owing to the merit of mechanical
excavation, excavation shall be done by nearly full face excavation method. It is called micro-
bench method (it is named full face method with auxiliary bench cut in the Table), which leaves
the lower bench by few meters from the upper bench excavation face. The lower half section is
excavated simultaneously or continuously with the excavation of upper half section. This
method can maintain the stability of the face more easily than full face excavation.
TABLE 9.5-2 CLASSIFICATION AND CHARACTERISTICS OF STANDARD
EXCAVATION METHOD
Division of Section Applicable
Excavation Method Advantages Disadvantages
of Heading Ground Condition
Common excavation method Labor saving by Full tunnel length cannot
for small section tunnel mechanized necessarily be excavated
Very stable ground for large construction by full face alone.
section tunnel (A=30m2) Construction Auxiliary bench cut will
Fairly stable ground for Management including be adopted as required.
medium section tunnel safety control is easy Fragment rocks from the
Full Face Method
(A˃50m2) because of the single- top of the tunnel may fall
Unfit for good grounds face excavation. down with increased
interspersed with poor energy & additional
ground that may require the safety measure are
change of the excavation required.
method
Comparatively stable Labor saving due to Difficult to switch to
ground, but difficult using mechanized other excavation method
the Full Face Method. construction when the face does not
Full-face excavation is made Construction stand up.
Full Face Method with difficult during construction. management including
Auxiliary Bench Cut Presence of some poor safety control is easy
ground in fairly good because of the single-
Bench length = ground. face excavation.
2~4m
Ground is fairly stable, but Alternate excavation of Alternate excavation

Full-face excavation is top heading and lower system elongates the
difficult. bench reduces construction period.
Long Bench equipments and
Cut manpower needs.
Bench length˃50m
Applicable to various Adaptable to change in Parallel excavation makes
ground such as softly the ground condition. difficult the balancing of
ground, swelling ground, cycle time for top heading
Bench Short Bench
and medium to hard rock and bench.
Cut Cut
ground. (The most
Method fundamental and popular
D ˂ Bench length≤
50m method.)
Deformation control of the Easy to make early Scaffolding is required for
excavated inner section is closure of the invert. the top heading
more urgently required than excavation.
Mini Bench in the case of the Short Selection for construction
Cut Bench Cut. machine tends to be
Squeezing ground that limited for top heading
require an early closure of
the excavated section
Bench length ˂D.
Ground of shallow Face stability is Displacement or
overburden where ground secured by dividing settlement during the
surface settlement is into small sections. removal of the diaphragm
required to be kept at a Ground Surface shall be checked.
Center Diaphragm Method minimum. settlement can be Time for diaphragm
Comparatively poor ground significantly reduced. removal is added to the
One method is to condition for a large section Divided sections of construction period.
provide a tunnel. heading are larger than The adoption of a special
diaphragm only to
9-14
Division of Section Applicable
Excavation Method Advantages Disadvantages
of Heading Ground Condition
the top heading, those used in the Side auxiliary method in the
while the other is to Drift Method, and tunnel is difficult.
provide both a top larger machines can be
heading and a used.
bench.
Bearing capacity of the Ground surface Small machines have to
ground is not sufficient for settlement can be be used for drift
adopting the Bench Cut reduced. excavation.
Method. Temporary diaphragms
Side Drift Method Ground of shallow can be more easily
overburden where ground removed than those of
surface settlement is center diaphragm
required to be kept at a method.
minimum.
Tunnel excavation is designed to be commenced from both portals. Excavation from the
western portal is in ascending direction. This eases the excavation by providing natural
drainage downward towards the portal. On the contrary excavation from the eastern portal is in
descending direction and drainage of groundwater shall be done by pumping.
9.5.3 Sequence of Tunneling
Figure 9.5-2 shows the overall flow chart of procedure of micro bench-cut excavation and
Figure 9.5-3 illustrates the sequence of excavation.
9-15
Mobilization of
Machine/Equipment
Auxiliary Method
1. long span fore-poling (with/
without injection)
2. fore-piling
Excavation Excavation
Upper Half Section Lower Half Section
Excavation & Mucking Excavation & Mucking
Support System Support System

Upper Half Section Lower Half Section
1. Primary shotcrete 1. Primary shotcrete
2. Steel rib 2. Steel rib
3. Installation mesh 3. Installation mesh
4. Secondary shotcrete 4. Secondary shotcrete
5. Installation rockbolt 5. Installation rockbolt
Installation of
Note Waterproof Sheet
①. Auxiliary method will be adopted for
the west/east portal and D -I -a/b zone.
②. Steel rib will not be installed for C II and
D I zone.
Lining Concrete
FIGURE 9.5-2 PROCEDURES OF MICRO BENCH-CUT EXCAVATION
9-16
FIGURE 9.5-3 SEQUENCE OF MECHANICAL EXCAVATION
(1) Tunnel excavation and support installation

Excavation from western portal
After finishing mobilization and preparation work at western portal area, which include
construction of water channel along small valleys at both sides of the tunnel and along a valley
in front of the tunnel, preparation of temporary yards at both sides of the tunnel and installation
of temporary facilities start. During this period slope in front of the portal shall be cut and
9-17
protected by shotcrete and rockbolts or by free-flame and provide yards for tunneling operation.
Portal excavation then starts. First 17.5m long section is to be excavated by applying DⅡ
Support Pattern with fore-poling. Fore-poling, 3m long, is constructed at first from the portal
slope and mechanical excavation starts at upper half section by the length of 0.75m to 1.0m and
immediately after excavation primary shotcrete is applied to stabilize the excavated surface.
Steel support, H150, is installed then and secondary shotcrete is carried out. Rockbolts are
drilled and fixed and mechanical excavation continues in lower half section and supports are
installed continuously. Then next cycle fore-piling is constructed and upper-half excavation
starts.
Thin shotcreting may be required for the excavation face area to stabilize the poor rock mass.
Tunneling continues till 17.5m long from the portal and then tunneling continues by applying
Support Pattern CⅡ towards eastern portal.
Whenever fore-poling or fore-piling is required it is executed before commencement of next
cycle excavation utilizing the H-steel support as a guidance. Fore-poling is 3m long and is
executed in every excavation cycle where required by designated support pattern. On the
contrary fore-piling is 12m long and after execution of fore-poling tunnel is excavated by 9m
long continuously through applying designed support. After excavation of 9m is completed next
fore-piling starts.
Fore-piling is generally installed in arch section with injection of cement material to reinforce
the area surrounding fore-piling. However, when it is required to provide water-tight zone
around the whole tunnel periphery fore-piling is installed with chemical injection to all the
periphery of tunnel including invert.
When mechanical excavation encounters hard sandstones giant breaker is to be used or several
holes are drilled by drilling jumbo to ease the mechanical excavation.
Excavation from eastern portal
In the eastern portal area construction activity can be started independently from tunneling in
western portal. Gentle slope is to be cut till about 8m coverage above the tunnel is ensured.
During the open cut activity existing village road shall be diverted. As for the groundwater
treatment in the portal area to minimize the groundwater level shall be referred to 9.7.1 (2).
After finishing preparatory work tunnel excavation starts. Support Pattern DⅡshall be applied
till the zones where chemical injection from surface has been carried out. Afterwards tunneling
continues by applying DⅡ-a Pattern which accompanies installation of fore-piling with
chemical injection to establish watertight structure. Tunneling in descending gradient is
scheduled to continue till about 520m from the portal. When tunneling from western portal
delays tunneling from eastern portal should be continued to further west.
(2) Lining Concrete
Secondary lining concrete, to be commenced from both portals, follows the excavation about
several hundred meters to thousand meters apart. Behind the lining concrete water-proofing
sheets are fixed in order to prevent the groundwater entering into the tunnel through joints and
cracks of the lining concrete.
In portal area where non-uniform overburden loads acting permanently lining concrete shall be
reinforced by steel bars but in other section steel reinforcement is not required. Arch shaped
steel-form is to be used for secondary lining concrete.
(3) Muck Disposal
Excavated material is loaded onto the dump trucks by shovel and is transported inside the
tunnel till portal area. Muck then shall be transported by dump-cars to the spoil disposal area. In
western portal muck is transported by dump truck to the disposal area in the valley in front of
portal. In the eastern portal muck will be transported by dump cars to the temporary storage
9-18
yards within the ROW area in approach road.
(4) Observation and Measurement
Observation and measurement is the key monitoring activity in NATM to confirm the stability
of the tunnel.
Observation of geotechnical condition of the excavated face and condition of already supported
tunnel are to be carried out as a daily activity and are to be recorded on the sheets and stored for
later review.
Measurement of the rate of deformation of the tunnel is to be carried out once a day at the face
area to confirm the adequacy of the support installed. If deformation rate of tunnel is larger than
expected then additional support is installed to confine the deformation. With the progress of
tunnel measurement behind the face area is to be done once a week or once a month and when
deformation is confirmed to have finished measurement is no more required there.
Measurement is generally done by electro-optical distance measuring instrument. It measures
the deformation of the tunnel by measuring the displacement of the monitoring pins fixed on
the shotcrete. Results of measurements are recorded in the data sheets and are analyzed after
each measurement whether tunnel is getting stability or not and are stored for later review.
Figure 9.5-4 shows the flow chart of observation and measurement.
FIGURE 9.5-4 FLOWCHART OF OBSERVATION AND MEASUREMENT

(5) Preservation of Groundwater Level
Along the tunnel alignment surface water flow and groundwater are utilized for various purpose
by inhabitants. Especially in the eastern portal area and Thosne Khola area tunnel passes in thin
rock cover and preservation of groundwater level shall be very important.
To preserve the groundwater level in the eastern portal area as much as possible, about 100m
long section of the tunnel from the portal is designed to be watertight. Chemical injection from
the surface ground or by the use of long- span fore-piling shall be done for this section of the
tunnel.
As for Thosne Khola area about 200m long tunnel section will be excavated using long span
fore-piling with chemical injection.
Whenever significant water ingress from the shotcrete surface is observed additional chemical
injection shall be carried out by drilling holes for injection.
9-19
(6) Drainage Inside the Tunnel
The tunnel is descending to the west and parts of the eastern approach road descends to the
tunnel. Thus it is important to manage the rainfall water adequately. Drainage system shall have
enough capacity for the future climate change also. Some of the rainfall water from the
approach road shall be drained off before entering into the tunnel adequately.
In the tunnel at both sides of the bottom of tunnel shall be equipped with U-shaped water
channel other than center drain. Water from the tunnel then shall be gathered at outside the
western portal into water storage tank and then discharged to the drainage system to be
provided in the valley in front of the tunnel or used for other purposes.
Details of drainage system shall be suitably studied and designed in Detail Design Stage.
9.6 AUXILIAR METHODS
Some of the auxiliary methods are already explained and being designed in the support patterns
such as fore-poling and fore-piling in Type DⅠ-a and b and Type DⅡand DⅡ-a.
When tunneling encounters very poor ground where excavation face is very difficult to self-
supporting, shotcreting for the face and rock-bolting for the face are required. Support pattern D
Ⅱ requires long span fore-piling with or without chemical injection depending on the rate of
ingress of groundwater. When tunneling encounters fault zones extra auxiliary measures such as
injection grouting to improve the strength of the poor ground is required. These auxiliary
measures shall be selected adequately in accordance with the nature of the ground encountered
during tunneling.
FIGURE 9.6-1 LONG SPAN FORE-PILING IN DIFFICULT GROUND
FIGURE 9.6-2 IMAGE OF EXECUTION OF LONG SPAN FORE-PILING

Figure 9.6-1 and Figure 9.6-2 shows the schematic view of long span fore-piling. Figure 9.6-3
shows the procedure of typical long span fore-piling, named AGF (All Ground Fastening).
9-20
Work inside tunnel for the
Work outside tunnel fault fracture zone
Construction of Portal Portion Excavation of Tunnel Portion
Preparation Work
1. Shotcrete for cutting face

2. Survey and marking for
drilling
3. Preliminary drilling
Drilling and Injection Work
1. Installation of AFG steel

pipe
2. Injection for consolidating
agent
Restart for Tunnel Excavation
FIGURE 9.6-3 PROCEDURE OF AGF
9.7 DESIGN OF TUNNEL PORTALS
Tunnel portal shall be located where slope is stable and natural drainage system is not harmful
for the structure. Preservation of natural environment is also required. Considering these issues
tunnel portals are fixed.
9.7.1 Eastern portal
Eastern portal is located in a very gentle slope where several houses exist and land is used for
agriculture. To reduce numbers of houses to be demolished or affected by tunneling as much as
possible, portal is fixed in the foot of the slope. Construction of the portal requires cutting of
the gentle slope to some extent. Cut slopes are protected permanently by shotcrete and
rockbolts or other slope protection measures and decorated by terraced flowers or grasses.
(1) Protection of houses near tunnel portal in eastern portal area
There are several houses near the tunnel portal. However, nearest house to the portal situates at
about 60m apart from the tunnel portal. Adequate slope protection is designed at the portal area
and tunnel excavation is to be done mechanically houses are not affected by tunnel construction
activities.
At No.2 + 700 there are two houses which are about 35m from the periphery of the tunnel.
Mechanical tunnel excavation at this distance has no influence to the stability of the houses and
very small level of vibration and noises are felt by the inhabitants.
Thus tunnel excavation as well as open cut excavation at the eastern portal area may not be a
harmful activities to the houses and residents.
9-21
(2) Treatment of groundwater at eastern portal area
Basic concept of the design (see Sheet NO. 21 of the Preliminary Design Drawings)
To minimize lowering of groundwater level at eastern portal area series of chemical injection is
designed. Objective of the chemical injection is to minimize the lowering of groundwater level
but not to get perfect watertight structures in the area.
In this concept and for the ease of open cut excavation in the area, groundwater level is to be
lowered to some extent along the slope above and east of tunnel.
· Open cut from No.2 + 880 to the east shall use gravity dewatering pumping well to lower
the groundwater level by about 3m.
· Zones from No.2 + 790 to No.2 + 880 shall be grouted by chemical injection from the
surface to the depth 3m deeper than finished grade of tunnel and road.
· Dimension of chemical injection is determined by the hypothesis that groundwater level
may be lowered by about 3m from the existing one through dewatering by gravity well
pump and dewatering by the weep holes in the retaining wall in the future.
Sequence of chemical injection is as following;
· Chemical injection from the surface at No.2 + 790 to No.2 + 820 where open cut of the
slope for tunnel portal starts.
· Chemical injection area is extended from here to both sides to cover the open cut
excavation of north and south walls.
· Chemical injection continues till No.2 + 880
· After completion of chemical injection works, open cut excavation starts from several
locations, from tunnel portal area and from east of it.
Longitudinal cross section and profile of the area for chemical injection from the surface is
shown in the Sheet NO. 21 of the Preliminary Design Drawings.
In the commencement of portal excavation long span fore-piling is to be carried out with
chemical injection. Figure 9.7-1 shows the typical example of the method.
Tunnel entrance structure will be similar to that shown in Figure 9.7-2.
(3) Drainage of the surface water
The small stream at southwest of the tunnel portal flowing to southeast shall be reconstructed
into new water channel in order not to inundate into the portal area during heavy rainfall. On
the cut slope in portal area water channels are designed to drain the rainfall to the outside of the
structure.
Rainfall waters from the approach road is designed to be drained by the water channels along
both sides of the road and are led to the underground water tank in the tunnel entrance and then
drained to western portal area through water channels fixed at both sides of the tunnel.
9-22
FIGURE 9.7-1 TYPICAL EXAMPLE OF PORTAL EXCAVATION USING LONG SPAN
FORE-PILING
FIGURE 9.7-2 TUNNEL ENTRANCE STRUCTURE
9.7.2 Western portal

(1) Slope stability
Western portal situates in the foot of cut slope beneath the moderately steep slope. Cut slope
9-23
shall be protected by shotcrete and rockbolts or by free-flame for permanent stability. Thus
required width of space is provided for the working space for tunneling. Tunnel is to be
connected to the existing road which is to be partially relocated.
Strikes of the strata in the slope in front of the tunnel are sub-parallel to the tunnel axis with
high dip angles, slope is generally stable here. However, the slopes at both sides of the tunnel
are rather instable due to the strikes of the strata which requires adequate protection measures
during construction.
While the rock mass in the tunnel portal area is deemed to be of Class CⅡ owing to the slope
cut, excavation of the portal area, 17.5m long, is designed to be constructed by D-Ⅱ pattern.
(2) Drainage system
In the small valleys at both sides of the tunnel which are scheduled to be used as temporary
construction yard for installation of temporary facilities and stock yard, water channels are
designed and led to the valley in front of portal where continuous channels, composed of 2m
diameter corrugate pipes, are designed which have enough capacity for the future climate
change (see Sheet App.10 of the Preliminary Design Drawings). Tunnel portal and new road
shall be protected by debris flow from these two small valleys and debris flow prevention dams
are designed accordingly.
Entrance structure of the tunnel may be similar to that shown in Figure 9.7-3.
FIGURE 9.7-3 TUNNEL ENTRANCE STRUCTURE
9.8 TEMPORARY FACILITIES AND EQUIPMENT NECESSARY FOR TUNNEL

CONSTRUCTION
Major temporary facilities consist of water treatment plant for contaminated water from the
tunnel, concrete batching plant for shotcrete and lining concrete, diesel generators for electric
supply, air compressors for shotcrete and other activities, ventilation fan and dust collector to
keep inside the tunnel clean and temporary houses for office and labor camps and so on. Detail
is shown in the Table 15.5.3-1 in Chapter 15.
9-24
9.9 FACILITIES NECESSARY FOR INSIDE AND OUTSIDE TUNNEL
9.9.1 General
Those mentioned below are facilities to be installed for the road tunnel (inside and outside) to
secure the safe and smooth traffic flow.
· Ventilation Facilities
· Lighting Facilities
· Emergency Facilities
· Others
(1) Facilities for the Inside of Tunnel
The facilities to be installed inside of tunnel are shown on Table 9.9-1.
TABLE 9.9-1 FACILITIES TO BE INSTALLED TUNNEL INSIDE
Facilities Name of Equipment
Tunnel Ventilation Jet fan, CO meter, VI meter, AV meter
Tunnel Lighting Interior Lighting, Entrance Lighting, Emergency Lighting
Emergency Facilities Emergency Telephone, Push Button Alarm, Fire Detector,
Fire Extinguisher, Fire Hydrant, Evacuation guide panel, Hydrant,
leaky coaxial cable, CC TV Camera, etc.
(2) Facilities for the Outside of Tunnel

Control Office will be constructed at West and East Portal Sites shown in Figure 9.9-1.
Control Office Detail of the Control Office
Control Office-1 Sub-control Office
(West Portal Side) Office Area: 390m2
Function:
- Administration building for toll-collection-related staffs
- Administration building for emergency staffs (support for main control office)
- Parking area of emergency vehicles
Facilities:
-Building
P Sub-Monitoring room and control room
P Equipment room
P Toll management room
P Staff room (Multiuse room)
P Others (Toilet, Kitchen, Nap room)
-Parking space (2 lots)
Control Office-2 Main Control Office
(East Portal Side) Office Area: 300m2
Function:
- Administration building for tunnel operation, monitoring, and maintenance
staffs (installation of related facilities)
- Administration building for toll-collection-related staffs
- Parking area of tunnel maintenance vehicles and emergency vehicles
Facilities:
-Building
P Main-Monitoring and Main-Control room
P Equipment room (Control panel etc..)
P Toll management room
P Staff room (Multiuse room)
P Others (Toilet, Kitchen, Nap room)
-Parking space (10 lots)
9-25
Control Office-1 (West Portal Side)
Control Office-2 (East Portal Side)

FIGURE 9.9-1 LOCATION MAP OF CONTROL OFFICE
The facilities to be installed outside of tunnel are shown on Table 9.9-2.
TABLE 9.9-2 FACILITIES TO BE INSTALLED TUNNEL OUTSIDE
Facilities Name of Equipment
Tunnel Ventilation Local control panel
Tunnel Lighting Lighting outside the Tunnel Entrance, Local control panel, etc.
Emergency Facilities Local control panel, Water supply Pump, Water tank, Pump panel,
Information board at tunnel entrance, Outside hydrant,
Emergency Telephone, Wireless terminal box, etc.
Others Electrical room, Management office,
Power supply system, Back up generator, UPS
Tunnel facilities remote control system, Remote monitoring
system,
Transmission system, , Building Facilities
9-26
9.9.2 Ventilation Facilities
(1) Purpose of Ventilation
The ventilation system is very much necessary to secure the safe and comfortable driving inside
tunnel; also it shall contribute for the better circumstance for the superintendants that are used
to manage the tunnel maintenance work. For that purpose, the important factor is to alleviate
the harmful substances from the emission of vehicles, which may cause the instinctive dislike,
and to make the good visual field.
(2) Design Criteria
It is recommendable to apply “Japan Road Tunnel Ventilation Standard on 2001” for
Nagdhunga Tunnel, in consideration of environment criteria and social conditions in Nepal.
(3) Design Conditions
The design conditions is described as mentioned below. It is considered upon the basis of
“Japan Road Tunnel Ventilation Standard on 2001” and some factor is added in taking account
of environment/social situation in Nepal.
· Length of Tunnel: 2,450m
· Longitudinal gradient: ＋3.22%（rising gradient from West to East）
· Tunnel altitude: average altitude is 1,340m
· Cross section of tunnel: 72.3m2
· Hydraulic diameter: 8.5m
· Traffic conditions: Two way traffic
· Designed velocity inside tunnel: 40km/h
· Expected traffic volume and mix rate of big-sized car
Year 2020：Traffic volume = 7,400 unit/day, Mix rate of big-sized car = 55.4%
The factors used for making Design Conditions are shown on the Table 9.9-3.
9-27
TABLE 9.9-3 FUTURE TRAFFIC VOLUME
(WITH SINDHULI RD: 2025, FAST TRACK RD: 2031)
Future traffic volume (with Sindhuli Rd：2025, Fast Track Rd.：2031)　①＝②＋③ （veh/day）
Year 2020 2025 2030 2035
Direction Eastbound Westbound Total Eastbound Westbound Total Eastbound Westbound Total Eastbound Westbound Total
Passenger Car 1,100 1,300 2,400 1,400 1,400 2,800 1,500 1,700 3,200 1,500 1,700 3,200
Micro Bus 500 700 1,200 500 700 1,200 600 900 1,500 600 900 1,500
Mini Bus 300 400 700 300 500 800 400 500 900 300 500 800
Large Bus 900 1,000 1,900 1,000 1,100 2,100 1,200 1,400 2,600 1,100 1,300 2,400
Light Truck 600 200 800 600 200 800 700 200 900 600 200 800
Heavy truck 1,200 1,800 3,000 1,300 1,900 3,200 1,600 2,100 3,700 1,000 1,400 2,400
Total 4,600 5,400 10,000 5,100 5,800 10,900 6,000 6,800 12,800 5,100 6,000 11,100
% Large 45.7% 51.9% 49.0% 45.1% 51.7% 48.6% 46.7% 51.5% 49.2% 41.2% 45.0% 43.2%
Number of Vehicles on Tunnel Section ② （veh/day）

Year 2020 2025 2030 2035
Passenger Car 900 900 1,800 1,100 1,000 2,100 1,200 1,200 2,400 1,200 1,200 2,400
Micro Bus 400 500 900 400 500 900 500 600 1,100 500 600 1,100
Mini Bus 0 0 0 0 0 0 0 0 0 0 0 0
Large Bus 800 800 1,600 900 900 1,800 1,100 1,100 2,200 1,000 1,000 2,000
Light Truck 500 100 600 500 100 600 600 100 700 500 100 600
Heavy truck 1,100 1,400 2,500 1,200 1,500 2,700 1,400 1,700 3,100 900 1,100 2,000
Total 3,700 3,700 7,400 4,100 4,000 8,100 4,800 4,700 9,500 4,100 4,000 8,100
% Large 51.4% 59.5% 55.4% 51.2% 60.0% 55.6% 52.1% 59.6% 55.8% 46.3% 52.5% 49.4%
Number of Vehicle on Existing road ③ （veh/day）
Year 2020 2025 2030 2035
Passenger Car 200 400 600 300 400 700 300 500 800 300 500 800
Micro Bus 100 200 300 100 200 300 100 300 400 100 300 400
Mini Bus 300 400 700 300 500 800 400 500 900 300 500 800
Large Bus 100 200 300 100 200 300 100 300 400 100 300 400
Light Truck 100 100 200 100 100 200 100 100 200 100 100 200
Heavy truck 100 400 500 100 400 500 200 400 600 100 300 400
Total 900 1,700 2,600 1,000 1,800 2,800 1,200 2,100 3,300 1,000 2,000 3,000
% Large 22.2% 35.3% 30.8% 20.0% 33.3% 28.6% 25.0% 33.3% 30.3% 20.0% 30.0% 26.7%
(4) Type of Ventilation System

There are several types of ventilation system i.e. longitudinal ventilation system, semi-
transverse ventilation system, transverse ventilation system and a combination of these types.
Longitudinal ventilation system, which is typified by the jet fan, is the most economical and
widespread system. Use of jet fans in particular is effective in terms of low running cost,
providing ventilation even if vehicles are queuing in the tunnel and removal of smoke in the
event of a fire.
(5) Required Air Volume
Required air volume in the tunnel and number of ventilation (jet fan) is calculated based upon
the factors described below.
1) Traffic volume per hour
The factor of calculation of ventilation system is dependent upon the time zone of peak hour for
the “traffic volume per hour” through the year.
The traffic volume per hour is calculated as follows;
Traffic volume per hour = 9,500 unit/day × K = 9,500 ×10% = 950 vehicles/hr
K = 7∼15％ in general, so 10 % is adopted for Nagdhunga Tunnel
9,500 unit/day = Traffic volume of Year 2030 (see 9.8.2-(3)), which contains Mix rate of big
sized car, γL=55.8%
2) Design value of Co and visibility
Acceptable environment design value of pollutants in the tunnel are shown in the Table 9.9-4
below.
9-28
TABLE 9.9-4 DESIGN VALUES FOR CO AND VISIBILITY
Visibility Transmissions
Item Design Velocity CO
(beam length: 100 m)
Above 80km/hr 50%

Design Criteria 100ppm
Below 60km/hr 40%
Nagdhunga tunnel 40km/h 100ppm 40%
3) Basic emission factor, speed & gradient factor and altitude factor
Table 9.9-5 indicates the basic-emission factor, speed and graduation compensating rate and
altitude compensating rate.
TABLE 9.9-5 BASIC EMISSION FACTORS
Particle matter (opacity) CO
Cars
Average (m2/km) Standard valuation (m2/km) Average (m3/km)
Big-sized car 5.1 2.3

0.007
Normal size car 0.5 0.7
Compensating rate
Compensating rate
Longitudinal gradient Altitude (m)

Speed & Gradient compensation factor for PM Altitude compensation factor for PM&CO
FIGURE 9.9-2 SPEED & GRADIENT COMPENSATION FACTOR AND ALTITUDE
COMPENSATION FACTOR
4) Required air volume and number of jet fan
The number of jet fans calculated by the figure of CO and visibility are shown on Table 9.9-6.
9-29
TABLE 9.9-6 REQUIRED AIR VOLUME AND NUMBER OF JET FAN
Mix rate of Required air volume
Traffic Number of Jet Fan (unit)
year Big-sized car (m3/s)
(no/hr/h)
(%) CO Visibility CO Visibility
2020 740 55.4 54 353 3 17
2025 810 55.6 58 388 3 21
2030 950 55.8 69 456 4 28
2035 810 49.4 58 353 3 17
The maximum number of jet fan shall be adopted; therefore, the number of jet fans shall be
twenty-eight (28) units in case of Nagdhunga Tunnel in consideration of 2030. Jet fan shall be
“JFX-1250” and those will be set at a distance of 160 m from the tunnel portal and at intervals
of 160 m in the tunnel.
It is considered that the traffic volume in Nagdhunga Tunnel will be reduced after 2030,
because the traffic will be diverted to the other new road, which is expected to construct by that
time.
50
45
% Large = 60.0%
% Large = 55.8%
40
% Large = 55.0%
Jet fan JF-1250 (35m/s)
% Large = 50.0%
35
% Large = 49.4%
% Large = 45.0%
30 28 units
JF-1250 (35m/s)
25
20
15
10
0
100 200 300 400 500 600 700 800 900 1000 1100 1200
Traffic [veh/h]
Traffic unit/hr
FIGURE 9.9-3 CORRELATION DIAGRAM FOR TRAFFIC VOLUME AND NUMBER OF

JET FAN
5) Specification of jet fan
Standard specification of selected jet fan (JFX-1250) is described on Table 9.9-7.
TABLE 9.9-7 STANDARDS SPECIFICATION OF JET FAN (JFX-1250)
Specification JFX-1250
Jet Fan Diameter of Fan (mm) 1250

Average Wind Speed (m/s) More than 35
Efficiency (%) More than 75
Noise (dB(A) Less than 95
Length (mm) 4250
Diameter (mm) 1450
9-30
Specification JFX-1250
Flow rate (m3/s) More than 43

2
Air flow area (m ) 1.23
Blow direction Both Side
Motor Type Three phase induction, drip proof type
Voltage (V) 400
Motor Power (kW) Less than 50
FIGURE 9.9-4 INSTALLATION OF JET FAN
PHOTO 9.9-1 JET FANS INSIDE TUNNEL
9-31
(6) Operation of Ventilation for 24 hours Estimation for 2030
The 28 units of jet fan shall be installed against the traffic volume per hour at the time of peak
hour. The operation frequency of 24 hours on someday of 2030 is estimated on Table 9.9-8.
However, the 0～11 units of jet fans may be enough with maneuvering the jet fans in opposite
current or vice versa when the traffic flow is not busy. In this case, the accumulated electric
energy for one day shall be 5,850 kWh.
TABLE 9.9-8 OPERATION FREQUENCY OF 24 HOURS (IN CASE 2030)
Direction East bound West bound Total (East + West) Nos. of JFX-1250
Traffic Large size Traffic Large size Traffic Large size Ventilation Direction
Time
[veh/h] [%] [veh/h] [%] [veh/h] [%] East bound West bound
7 270 77.4 182 44.8 452 64.3 9 15
8 198 70.6 325 41.2 523 52.3 9 8
9 238 56.0 365 44.0 603 48.8 10 8
10 319 47.9 283 42.7 602 45.5 9 11
11 295 35.6 266 42.9 561 39.1 7 7
12 233 40.8 304 47.2 537 44.4 8 5
13 227 43.4 323 50.3 550 47.4 8 5
14 240 36.1 281 51.0 521 44.1 7 5
15 310 37.1 283 51.6 593 44.0 8 8
16 262 33.3 313 59.1 575 47.3 9 5
17 270 33.8 270 60.4 540 47.1 8 5
18 283 22.0 304 69.2 587 46.4 9 3
19 237 34.1 241 81.7 478 58.1 8 4
20 186 46.2 226 91.0 412 70.8 9 4
21 102 36.4 264 94.6 366 78.4 9 0
22 64 35.7 138 90.4 202 73.1 5 1
23 92 53.0 91 89.9 183 71.4 3 2
0 44 48.9 26 81.9 70 61.1 2 2
1 49 61.7 16 96.1 65 70.3 2 2
2 57 70.9 7 27.2 64 66.2 1 3
3 71 65.6 4 75.9 75 66.2 1 3
4 168 86.2 20 69.9 188 84.4 2 9
5 297 97.6 50 83.6 347 95.6 10 24
6 287 95.3 117 67.1 404 87.1 11 22
9.9.3 Tunnel Lighting Facilities

The lighting of the tunnel is very important for securing traffic safety inside the tunnel.
(1) Lighting Composition
Tunnel lighting is composed of Primary Lighting, Entrance Lighting, Back Up Lighting (in case
of power cut), and Approach Lighting.
9-32
Traffic Direction
Tunnel
Entrance Interior Entranc e
Note Primary Lighting

Entrance Lighting
Approach Lighting
FIGURE 9.9-5 COMPOSITION OF TUNNEL LIGHTING
(2) Light Source

The following factors shall be considered for the selection of lighting sources.
· High efficiency with long life
· Accommodating against to high temperature, durability and humidity
· Appropriate luminescent color
· High luminous flux to meet the required high lighting level
· Easy maintenance
· Low running cost
1) Interior Lighting
Basic lighting levels are determined by the visual distance for the safety driving and not feeling
discomfort under the certain velocity, and it shall be provided whole length of the tunnel.
2) Entrance Lighting
Entrance lighting is provided to adjust the difference between the brightness outside tunnel and
relatively dark area inside tunnel, especially it happens in day time. Therefore, the lighting at
entrance area shall be more luminous than inside of tunnel, so that the driver shall be able to
adopt the difference of brightness.
3) Emergency Lighting during Power failure
In case of a sudden loss of power, emergency lighting is required to prevent visual obscuration
for the drivers already running in the tunnel. Power shall be supplied from the UPS
immediately as uninterruptible power source, and subsequently it shall be connected to the
back-up generator.
4) Lighting outside the Tunnel Entrance
The street ramp at the exit of tunnel shall be installed adequately to guide the drivers coming up
from the tunnel, especially in nighttime. No street ramp at the exit road may cause the
constriction of the visual field of drivers, and may lead the accidents. This street ramp may be
applicable with the same type of street ramp used in Kathmandu City.
9-33
5) Selection of Light Source
LED lighting is used in common against the conventional light fixtures, because the overall
cost is less in respect of durability and power consumption. Therefore, it is recommended to use
LED lightings.
Interior Lighting(LED)
Back Up Lighting
(lighting system in case
of power cut)
Entrance lighting
Lighting outside
the Tunnel Entrance
PHOTO 9.9-2 TUNNEL LIGHTING (LED)
9.9.4 Tunnel Emergency Facilities

(1) General
Tunnel Emergency Facility is the equipment and devices to prevent the accidents caused by the
fire inside of tunnel. Counter disaster measures for tunnel are divided into two objectives,
9-34
which are:
· Prevention of accident
· Minimization of damage from accident
Prevention measures are basically composed of education of tunnel users such as i) to learn the
potential of accident in tunnel, ii) cooperation to the tunnel administrators with using the
emergency services, and iii) provision of a comprehensive safety and surveillance control
system. Counter disaster measures will be carried out not only by the staff of the tunnel
management office, but also by the tunnel users themselves. Therefore, public involvement is
very important.
(2) Classification of Tunnel and Installation of Emergency Facilities
The tunnel length of 2,450m with daily traffic of 9,500 (as of 2030) is classified for “Class A”
tunnel as depicted on Figure 9.9-6, which is specified on “Japanese Road Tunnel Safety
Standard”.
FIGURE 9.9-6 CLASSIFICATION OF TUNNEL
9-35
The class A tunnel requires provision of emergency facilities, as shown on Table 9.9-9.
TABLE 9.9-9 INSTALLATION STANDARD OF EMERGENCY FACILITIES
Classfication of tunnel
AA A B C D Remarks
Facilities
Emergency Telephone ○ ○ ○ ○
Information and Alarm Facility
Push Button Alarm ○ ○ ○ ○
To be provided in Class A tunnel with Ventilation System

Fire Detector ○ △
or Water sprinkler system.
Emergency
○ ○ ○ ○ Information board at tunnel entrance
Information board
Fire Extinguisher ○ ○ ○
Fire Fighting
Facility
Fire Hydrant ○ ○
Evacuation Guide
Guide Board ○ ○ ○
Facility
Ventilation system shall be used for smoke removal.

Smoke removal system
Evacuation tunnel shall be provided for Class A tunnel,
or ○ △
3000m or more in length, bidirectional traffic and
Evacuation route
longitudinal ventilation system.
Hydrant ○ △ To be provided in Class A tunnel with Fire hydrant.
To be provided in Class A tunnel 3000m or more in length.

Radio communication
○ △ Required and recommended for tunnel Operation and
support System
Maintenance.
Other Emergency Facilities

Radio Rebroadcast
○ △ Required and recommended for tunnel Operation and
System
Maintenance.

Loud Speaker System ○ △
Class A tunnel with evacuation passage.
Water sprinkler system ○ △ To be provided in Class A tunnel 3000m or more in length.
To be provided in Class A tunnel with Water sprinkler

Monitor System ○ △
system.
Note：　○：Mandatory(standard)　　△：Recommended
(3) Type of Emergency Facilities

Following emergency facilities will be planed based on “Japanese Road Tunnel Safety
Standard”.
Provision of TV cameras to monitor the traffic conditions inside the tunnel is not required by
the Japanese Standard. However, this can enable visual monitoring of traffics for obtaining
prompt and reliable information of traffic condition inside and outside the tunnel. Therefore, it
is decided to facilitate TV cameras in Nagdhunga Tunnel.
9-36
TABLE 9.9-10 EMERGENCY FACILITIES
Safety System Contents Detail
Information and Alarm Emergency Telephone
Facility Push Button Alarm
Fire Detector
Emergency Information board Information board at tunnel
entrance
Fire Fighting Facility Fire Extinguisher Portable fire extinguisher
Fire Hydrant
Evacuation Guide Guide Board Evacuation guide panel(LED)
Facility Smoke removal system Ventilation System
Other Emergency Hydrant
Facilities Radio communication support Wireless Radio System
System
Radio Rebroadcast System
Monitor System CCD TV Monitoring System
1) Emergency Telephone
Emergency Telephones will be set at both entrances and at intervals of 200 m in the tunnel.
Emergency Telephone on Emergency Telephone at

Emergency Telephone Box
wall entrance
2) Push Button Alarm

Push button alarm system will be set 1.2 to 1.5m above road surface and at intervals of 50 m.
This alarm system will connect with the emergency telephone and fire fighting system.
9-37
Push Button Alarm with Extinguisher & Fire Hydrant
3) Fire Detector
Fire Detector will be set in the tunnel for automatic detection of fire and at intervals of 50 m.
The tunnel entrance information board, lighting system, fire fighting facilities and ventilation
system will be operated automatically or receiving a signal from an automatic fire detector.
Fire Detector
4) Emergency Information board

Emergency alarm system will include both visual signals and audible alarm. Flashing lights
instructions given by loudspeaker will be effective for aiding evacuation of user.
The information boards must have sufficient communication ability to inform users of
conditions inside the tunnel. Information boards shall be set at appropriate locations to avoid
any disturbance to fire fighting and/or evacuation of users.
Information board at entrance Control panel
9-38
5) Extinguishers
Extinguishers shall be set at intervals of 50m.
6) Fire Hydrants
Setting interval of Fire hydrants is the same as extinguishers, 50m.
Extinguisher & Fire Hydrant
7) Guide Boards
Guide boards are illuminated signs to inform the location of Tunnel portal to road users. Guide
board shall be set at t intervals of 200m.
Guide Board (LED)
8) Smoke removal system

The tunnel ventilation system shall be used both as a Smoke removal and tunnel ventilation. Jet
fan will act to extract smoke in the event of fire in the tunnel.
Smoke removal system (Jet Fans)
9) Hydrants
Hydrants shall be set at intervals of 200m in the tunnel inside the fire hydrant box. Outdoor
Hydrants for use outside the tunnel shall be set at both tunnel entrances.
9-39
Outdoor Hydrant
10) Wireless Radio System

Coaxial cable shall be set under the tunnel lighting system or the tunnel center wall to allow for
use of radios by tunnel staff and the emergency services.
Wireless terminal box Coaxial cable
11) Radio Re-broadcasting System

Radio re-broadcasting system is secure radio broadcast in tunnel using lead antenna at tunnel
entrance. When an emergency occurs in the tunnel, the system shall be used to transmit
emergency information radio signals to car users in the tunnel.
Guide Wire for AM Radio
9-40
AM aerial wire Radio Receiving Panel
12) Monitor System

The monitor camera system is designed based on the tunnel plan and profile, focal length of
cameras, and the size of objectives. Camera shall be installed at 2.8m above road surface, and
those shall be installed at Emergency Parking Bay and 150～200m intervals of tunnel.
Arrangement of tunnel equipment is shown in the Sheet NO.22 of the Preliminary Design
Drawings.
FIGURE 9.9-7 INSTALLATION OF CABLE, WATER SUPPLY, CCTV CAMERA, ETC.
9.9.5 Power Supply System

(1) General
This section is summarizing power supply and back-up system. The back-up system will cover
the lighting, 4 units of ventilation fan, water supply and others, which is required minimum
function to secure the safe and adequate driving.
9-41
(2) Design condition
· Frequency: 50Hz
· Location of Power Supply System: East Electrical room

West Electrical room
(3) Design Load

The following table shows loads of each system.
TABLE 9.9-11 LIST OF LOADS AT EAST ELECTRICAL ROOM
Capacity of Transformer
Total Load (kVA)
kVA
Ventilation 1 523.2 750
Ventilation 2 & Power 431.6 750
Lighting & Others 202.0 300
Total 1156.8 1,800
TABLE 9.9-12 LIST OF LOADS AT WEST ELECTRICAL ROOM

Capacity of Transformer
Total Load (kVA)
kVA
Lighting & Others 202.0 300
Total 1117.6 1,800
TABLE 9.9-13 LIST OF LOAD FOR EAST ELECTRICAL ROOM

Capacity
Application Source / Voltage
kW kVA
Jet Fan-1 AC 3φ3W 415V 50 65.4
Jet Fan-2 AC 3φ3W 415V 50 65.4
Jet Fan-3 AC 3φ3W 415V 50 65.4
Jet Fan-4 AC 3φ3W 415V 50 65.4
Jet Fan-5 AC 3φ3W 415V 50 65.4
Jet Fan-6 AC 3φ3W 415V 50 65.4
Jet Fan-7 AC 3φ3W 415V 50 65.4
Jet Fan-8 AC 3φ3W 415V 50 65.4
Sub-total 523.2
Jet Fan-9 AC 3φ3W 415V 50 65.4
Jet Fan-10 AC 3φ3W 415V 50 65.4
Jet Fan-11 AC 3φ3W 415V 50 65.4
Jet Fan-12 AC 3φ3W 415V 50 65.4
9-42
Capacity
kW kVA
Jet Fan-13 AC/GC 3φ3W 415V 50 65.4
Jet Fan-14 AC/GC 3φ3W 415V 50 65.4
Fire Fighting Pump AC/GC 3φ3W 415V 30 39.2
Spare AC 3φ3W 415V -
Sub-total 431.6
Lighting control AC 3φ3W 415V 1.0
Entrance Lighting -1 AC 3φ3W 415V 13.0
Interior Lighting -1 AC 3φ3W 415V 5.0
Lighting outside TN -1 AC 3φ3W 415V 0.5
Sub-total AC 3φ3W 415V 115.0
Interior Lighting -4 AC/GC 3φ3W 415V 2.0
Guide Board -1 AC/GC 3φ3W 415V 2.0
Spare AC/GC 3φ3W 415V -
Sub-total AC/GC 3φ3W 415V 4.0
Interior Lighting -5 INV 3φ3W 415V 2.0
Emergency Information board INV 3φ3W 415V 2.5
Others INV 3φ3W 415V 6.0
Spare INV 3φ3W 415V -
Sub-total INV 3φ3W 415V 12.5
CCTV Camera in TN INV 1φ2W 210V 2.5
9-43
Capacity
kW kVA
CCTV Camera outside TN INV 1φ2W 210V 0.5
Subtotal INV 1φ2W 210V 3.0
Control Panel -1 INV 1φ2W 105V 2.5
Power -1 AC/GC 3φ3W 210V 5.0
Subtotal AC/GC 3φ3W 210V 48.0
Panel -1 AC/GC 1φ2W 105V 1.0
Total 202.0
9-44
TABLE 9.9-14 LIST OF LOAD FOR WEST ELECTRICAL ROOM
Capacity
kW kVA
Jet Fan-1 AC 3φ3W 415V 50 65.4
Jet Fan-2 AC 3φ3W 415V 50 65.4
Jet Fan-3 AC 3φ3W 415V 50 65.4
Jet Fan-4 AC 3φ3W 415V 50 65.4
Jet Fan-5 AC 3φ3W 415V 50 65.4
Jet Fan-6 AC 3φ3W 415V 50 65.4
Jet Fan-7 AC 3φ3W 415V 50 65.4
Jet Fan-8 AC 3φ3W 415V 50 65.4
Sub-total 523.2
Jet Fan-9 AC 3φ3W 415V 50 65.4
Jet Fan-10 AC 3φ3W 415V 50 65.4
Jet Fan-11 AC 3φ3W 415V 50 65.4
Jet Fan-12 AC 3φ3W 415V 50 65.4
Jet Fan-13 AC/GC 3φ3W 415V 50 65.4
Jet Fan-14 AC/GC 3φ3W 415V 50 65.4
Sub-total 392.4
Lighting control AC 3φ3W 415V 1.0
9-45
Capacity
kW kVA
Subtotal AC 3φ3W 415V 115.0
Interior Lighting -4 AC/GC 3φ3W 415V 2.0
Emergency Information board INV 3φ3W 415V 2.5
Others INV 3φ3W 415V 6.0
CCTV Camera in TN INV 1φ2W 210V 2.5
CCTV Camera outside TN INV 1φ2W 210V 0.5
9-46
Capacity
kW kVA
Total 202.0
Total load demand in MW shows below.

2MW (East Electrical Room:1MW, West Electrical Room:1MW)
1.Ventilation Jet-fan 28 unit* 50kW =1,400kW

2. Tunnel Lighting =300kW
3. Others =less than 300kW
Total 2,000kW
(4) Transformer Capacity

Transformer capacity of each Electrical room is as follows:
1) East Electrical room
· Ventilation Transformer No.1: 750kVA
· Transformer for Lighting: 300kVA
2) West Electrical room
(5) Un-Interruptible Power Supply System
Un-Interruptible Power Supply System shall be installed for the following systems which need
electricity all the time.
· Tunnel Information Board
· CCTV System
· Safety system control panel
9-47
· Remote control system
Capacity of Battery is as follows:
· UPS: 30kVA
· UPS: 30kVA
(6) Back Up Generator
Capacity of back-up generator is as follows:
· Generator Capacity: 300kVA
· Generator Capacity: 300kVA
The back-up generator system can provide the minimum functions of tunnel lighting,
emergency facilities’ operation in case of power cut. The back-up generator will be installed for
300 kVA at each Electrical room.
The planed back-up system will cover the quarter of lighting (only one side, alternating on and
off), 4 units of jet-fan, fire hydrant, CCTV camera and control systems, which is required
minimum function to secure the safe and adequate driving. Based on the estimation of
ventilation, 4 units of jet-fan will handle 14hours operation in year 2030.
Un-Interruptible Power Supply System shall be also needed to maintain the minimum functions
of tunnel lighting and emergency facility’s operation during unstable condition of back-up
system after just power cut (approximately 10 minutes).
9.10 DISPOSAL AREAS OF EXCAVATED MATERIAL
For shortening the construction period, the tunnel excavation is planned to excavate from the
east and west portals. Excavated material of about 52,000 cubic meters comes out from the
eastern portal and about 176,000 cubic meters from the western portal.
9-48
No.3 Khani Khola No.1 Sisune Khola
Tunnel
No.2 Thapathok
Road
FIGURE 9.10-1 LOCATION MAP OF DISPOSAL AREA

Excavated material out of the eastern portal is planned to be used as fill material for road.
Excavated material from western portal is about 176,000 cubic meters and after reviewing
several conditions as below listed Sisune Khola valley was selected as spoil disposal site among
the three candidate sites shown in the Figure 9.10-1.
1. Disposal site shall be close to the tunnel portal for the economy of transportation
2. Disposal site that can contribute to the improvement of the road
3. Disposal site becomes a meaningful place for local residents and road users
4. Compensation for agricultural land is less
Three candidate sites shown in Table 9.10-1 were compared from above points of view.
TABLE 9.10-1 COMPARISON OF DISPOSAL SITE
No. Place Distance Volume Feature Comparison
1 Sisune 100m 300,000 · Close to the tunnel ◎
khoka · Secure the land required for the road
improvement
· Installation of tunnel management
facility
· Effective use of the tunnel drainage
2 Thapathok 5.3km 140,000 · Substantially horizontal land can be △
used
· Current road can be shortened by 150m
· Shortage in capacity
3 Khanikhola 8.3km 125,000 Nice view, agricultural products gather △
from near village, useful for such as Road
Station
· 5 houses
· Shortage in capacity
9-49
9.11 PLANNING OF POWER TRANSMISSION SUPPLY FACILITY
9.11.1 Identification of NEA grid Substation for Power Supply to the Tunnel
For Power supply to the tunnel operation the nearest located Nepal Electricity Authority (NEA)
Grid Substation is 132/11kV Substation at Matatirtha.
NEA has already started construction of 60 MW Trishuli 3A, 38 MW Trishuli 3B, 14.6 MW
Upper Sanjen, 42.5MW Sanjen , 111MW Rasuagadhi, 5MW Tadi khola, 4.2 MW Tharpek, 102
MW Upper Trisuli -2 and 5 MW Upper Mailung-A are some other projects being considered
connected to the National Grid.
A new 220/132/33kv Substation is being built nearby Upper Trishuli 3B HEP which acts a Hub
for the evacuation of Hydro Electric Power generated in Trishuli 3B Hub 220/132kV Substation
Project in the Trishuli region. This Substation will be connected with 220 /132kV Matatirtha
S/S in Kathmandu by 220 kV double Circuit Distribution line which is in construction stage.
The existing space at 132/11 kV substation at Matatirtha is congested and to house the
220/132kV substation the substation area has to be extended and accordingly NEA has initiated
the land acquisition procedure for its extension and for this NEA has published public notice to
acquire the required land, on 26 September 2014 and the whole Project work of expansion is
expected to be complete within 2016.
With this extension of Matatirtha Substation area, it is easier to plan the route alignment for the
outgoing 11kV feeders from the Matatirtha substation, compared to the present condition. But
still the problem of fast urbanization causes public grievances for Distribution line alignment.
Because of this extension of Substation area in Matatirtha, Distribution line outlet from this
Substation to Tribhuvan Highway has been easily possible through cable trenching.
A 22 MVA, 132/11kV, 3 Phase Transformer is installed in Matatirtha Substation to supply the
local feeders.
For 11kV Power Supply to Tunnel Operation a separate reliable and dedicated 11kV double
circuit transmission System is required and accordingly two separate 11kV feeders are planned
from 132/11kVMata Tirtha Substation to the east control room located at tunnel portal and
from here by 11kVcable laid on the cable tray anchored on the one side of the tunnel the 11kV
Power will be fade to the west control room located at tunnel out let portal.
i) Principally it is possible to have dedicated Power Supply system for the tunnel operation as
the ventilation fans and light loads should be fed without any frequent Power outage are
vital for movement of vehicles inside the tunnels. For obtaining dedicated 11kV double
circuit Distribution line for tunnel operation necessary procedure and applications will be
submitted as per NEA Electricity Act at the tunnel construction time.
At Matatirtha Substation 11kV VCBs of ABB Italy made are installed for supply to local
feeders and its panel drawings are shown Figure 9.11-1.
9-50
FIGURE 9.11-1 PANEL DRAWING AT MATATIRTHA SUBSTATION
For Power supply to tunnel operations two VCBs of the same make is proposed to install by
extending the 11kV bus and by doing so no adaptation panel will be required.
9.11.2 Power Supply to Tunnel Operation
To supply Power to the tunnel, two control rooms one near to the west wide tunnel portal (West
Control Room) and another near the east side tunnel portal (East Control Room) are planned.
Basically the tunnel length is 2.45KM long and have jet-fans for ventilation and lights among
other facilities. For supply of power to these facilities, an estimated total of 3600 KVA, 11/4.0
kV is required. Two 750KVA, 11/0.4kV and one 300KVA, 11/0.4kV transformers are planned
to be installed at the west side control room. Similarly, two750KVA, 11/0.4kV and one
300KVA, 11/0.4kV transformers are planned for installation at the east side control room.
The basic concept to design two control room each of them housing 2x750 kVA transformers
and 300kVA transformers of voltage 11/0.4kV at each tunnel portal is that, the one set of
ventilation and light loads is fed from east control room and other set of ventilation and light
loads is fed from west control room and doing so it minimizes the voltage loss in 400Volt
cables, as the length of cable will be halved.
9.11.3 Transformer Capacity
Transformer capacity of each Electrical room is as follows:
(1) East Electrical room
(2) West Electrical room
9-51
9.11.4 Un-Interruptible Power Supply System
Un-Interruptible Power Supply System shall be installed for the following systems which need
electricity all the time.
· Tunnel Information Board
· CCTV System
· Safety system control panel
· Remote control system
Capacity of Battery is as follows:
(1) East Electrical room
· UPS: 30kVA
(2) West Electrical room
· UPS: 30kVA
9.11.5 Selection of 11kV Cable size for Power Supply
Calculation for 11kV Cable size :
Total Transformer Capacity
East Control room 1800KVA
West Control room 1800KVA
Total load 3600 KVA
Current (I) =236.195675Amps
XLPE Cable size for 3600 KVA shall be
a) 240Sq.mm( resistance =0.1618Ohm/km) or
b) 300 Sq.mm size ( resistance= 0,1302Ohm/KM)
Voltage drop =199.7268 V
Receiving end voltage =10654.06 V
240Sq.mm (resistance =0.1618Ohm/km) Aluminum Cable can be selected but for safe
margin Aluminum cable is preferably 300 Sq.mm is selected.
Hence two Nos. of 300 Sq.mm, Aluminum Cable are selected for two 11kV Distribution line
circuits to be tapped to feed each of the 2x750 kVA and 300 KVA ,11/0.4kV transformers
located at east and west control rooms for tunnel operation.
9.11.6 11kV Power supply feeder from 132/11kV Matatirtha Substation to East and West
Control rooms for Tunnel operation.
Matatirtha Substation is located near to densely populated area of Thankot a lot of congested
houses are seen and the roads are narrow and the no free space available to locate the 11kV
Distribution line poles. Moreover the NEA has constructed cable trench for outgoing 11kV
distribution feeders from this substation and the cable duct is full and no space is left for new
cables in it. For future outgoing Distribution line feeder a new Distribution line route
alignment or cable duct route is to be planned.
An extensive site survey to identify a viable 11kV outgoing Distribution line feeder alignment
from this 132/11kV substation to Naghdhunga Power supply system was conducted. The
information of upgrading program of 132/11kV Substation to accommodate the 220/132kV
substation in the same substation premises with extension of the substation area and the
progress of land acquisition was collected.
The 132/11kV Matatirtha Substaion is seen in the Google map. The proposed extended
substation area is shown in Figure 9.11-3 and the boundary line is shown in red. The land
acquisition to extend the substation is under process.
9-52
Tunnel Total Length: 4.14 km
Underground Cabling: 1.95 km
Overhead Transmission: 2.19 km
Overhead Transmission
L=2.19 km
Exciting Road
Underground Cabling:
L=1.95 km
FIGURE 9.11-2 ENTIRE DISTRIBUTION LINE FROM MATATIRTHA SUBSTATION

TO TUNNEL EAST PORTAL
To Tunnel Overhead Transmission

2.19 km
Highway Crossing
Public Road
(4m wide)
Underground Cabling 1.95 km

Cover by concrete box or PVC pipe
Proposed
Expansion of SS
FIGURE 9.11-3 DISTRIBUTION LINE FROM MATATIRTHA SUBSTATION TO

HIGHWAY CROSSING POINT
9-53
FIGURE 9.11-4 DISTRIBUTION LINE FROM HIGHWAY CROSSING POINT TO
TUNNEL EAST PORTAL (WITH TOWER LOCATION)
9.11.7 Transformers
To supply 11kV to the 2x750 and 300KVA Transformers installed in the
a) East control room
b) West control room
The following measures shall be taken
1) From 132/11kV Matatirtha Substation two outgoing 300Sq.mm, 3 core aluminum,
armored cables for 11kV double circuit Distribution line feeder shown in green color in
the Google map will be buried in cable duct of 1.95Km long
The path of the 11kV cable duct 1.95 Km long is shown in the Google map and is
described as follows
a) The 11kV cable duct starts from Matatirtha Substation
b) passes through a narrow road between the houses in both sides
c) reaches to a point near to the highway from where it follows parallel to the road
d) and it crosses the road
2) After crossing the road the each of the two cables will be connected to its relevant 11kV
circuit of overhead Distribution line circuit. The double circuit Distribution line is 2.19
KM long and follows along the approach road to the tunnel portal where the east control
room is located. The route map is attached.
3) Both circuits of the 11kV Distribution line shall be connected to 11kV bus in east
control by respective cables. To supply to the west control room from the 11kV bus
located in easrt control room an outgoing nearly 2.35 KM long, 240Sq.mm, 3core,
armored Aluminum cable will be laid in the cable rack anchored on one side of the
tunnel wall and then after passing out from the tunnel the cable will be connected to
11kV bus of east control room to supply power to 2x750 and 300 KVA transformers
located here to supply Power to the tunnel operation.
4) SLD
A SLD for Power supply containing all the equipments from the interconnection Substation to
the control rooms located at Tunnel inlet and out let portals
9.11.8 Brief description of the VCBs in the SLD
a) From 132/11kV Matairtha Substation for double circuit 11kV outgoing Distribution line
feeder following arrangements are necessary:
1) 3core, 300sq.mm, Armored, Aluminum cable for each of the outgoing feeders for tunnel
operation
2) 2Nos of VCBs of 1250 A rating for the outgoing feeders to be installed at Matatirtha
Substation
9-54
3) 2 Nos. of VCBs of 1250 A rating for the outgoing feeders to be installed at East Control
room
4) One sectionalizing VCB of 1250 A to be installed at East control room 11kv bus
5) 11kV double circuit overhead Distribution line
6) 3 Nos. of VCBs of 630 A for protection of the distribution transformers for east control
room
7) 3 Nos. of VCBs of 630 A for protection of the distribution transformers for west control
room
8) Estimation
9.11.9 Cost Estimation
Based on the equipments shown in the SLD and the design philosophy described above the cost
estimation is prepared and attached herewith.
The Bill of quantities for Power Supply to Tunnel operation prepared includes basically
following costs
a) The cost of the equipments to be incurred at the NEA interconnecting substation at
132/11kV Matatirtha Substation ,
b) The cost of 11kV cables laid on the cable trench from Matatirtha substation to the road
crossing , HDPE Pipes and joints pipes for 11kV cables installation works,
c) Cost of civil works of cable trench ,
d) Cost of overhead 11kV double circuit Distribution line starting from the end point of cable
trench and following the approach road to tunnel portal ,
e) Cost of equipments to be installed in east and west control rooms
f) Cost of 11kV cable to be laid at the cable rack on tunnel side wall for supply of Power to
west control room from east control room
g) The cost of the backup 300KVA diesel engine considered in the design is not included in
the BOQ as the information received is the diesel engines used in construction will be
utilized for operation time of tunnel to save cost.
The BOQ is prepared and attached herewith revel that for Power Supply to the tunnel operation
at least a fund of USD 1,499 thousands is required.
The Summary Table of the Cost breakdown is shown in the Table 9.11-1.
TABLE 9.11-1 COST ESTIMATION OF THE ELECTRICAL WORKS FOR POWER
SUPPLY TO TUNNEL VENTILATION AND LIGHTING
Item No Description Totals US$
1 11kV ABB Italy made Vacuum Circuit Breakers (VCB) 171,800
2 Other VCBs 146,880
3 Distribution Transformers 204,975
4 11kV double circuit Distribution line 204,564
5 Air Circuit Breakers (ACBs) 19,217
6 Aluminum Cable, HDPE Pipes and Pipe Joints (from Matathirtha SS to East Control Room) 252,252
6.2 HDPE Pipes 140mm 5 inches diameter 6kg/sq.cm 63,063
6.3 HDPE Pipe Joints 7,453
7 Aluminum Cable, HDPE Pipes and Pipe Joints (from East Control Room to West Control Room) 131,576
8 Civil works of cable trench (from Matathirtha SS to Highway Crossing) 107,388
11kV Cabling works on cable racks installed on left side wall of the tunnel for supply of Power to west
9 30,030
control room from east control room . from East Control Room to West Control Room.
10 Others 160,000
Total Costs 1,499,198
9-55
Refer to Annex 9.11-1 for details of the Cost Estimation.
9.12 FACILITIES NECESSARY FOR TUNNEL O & M
(1) Tunnel Management Office

Safe operation of a tunnel require the creation of a Tunnel Management Office, thorough
discussion of this can be found in Section 14.2.
(2) Toll Collection Facility
In order to secure the tunnel O & M cost, toll collection facilities was designed.
1) Required Toll Booth Number
In accordance with traffic demand forecast (see section 5.2), the required toll booth was
calculated. Toll Booth will be installed at each tunnel entry point to check dangerous car, over
weight car and etc.
TABLE 9.12-1 PEAK HOUR TRAFFIC VOLUME AT TUNNEL SECTION
AADT Peak hour Peak Traffic
2030 (a) (b) Volume(c= a × b)
Eastbound 5,000 veh /day 6.3 % 315 veh/hr
Westbound 4,800 veh/day 6.3 % 302 veh/hr
In Japan, the average service time at toll gate is 8 second in case of flat rate. But study team
assumed the average service time at toll gate is 10 second for this project. Table 9.12-2 shows
the required toll booth, service time and average waiting vehicle at gate. As peak traffic volume
is 302 ~ 315, the minimum required toll gate is two (2) booths for average one waiting vehicle
level. The study team recommended three (3) booths for eastbound (west-side) considering one
spare booth.
TABLE 9.12-2 SERVICE TIME, AVERAGE WAITING VEHICLE AT TOLL GATE AND NO.
OF TOLL GATE
Service
Time 6 sec 8 sec 10 sec 14 sec 18 sec 20 sec
Ave. Waiting
Vehicle at Toll
Gate
No. of 1.0 3.0 1.0 3.0 1.0 3.0 1.0 3.0 1.0 3.0 1.0 3.0
toll gate
1 300 450 230 340 180 270 130 190 100 150 90 140
2 850 1,040 640 780 510 620 360 440 280 350 250 310
3 1,420 1,630 1,070 1,230 850 980 610 700 480 550 430 490
4 2,000 2,230 1,500 1,670 1,200 1,340 860 960 670 740 600 670
5 2,590 2,830 1,940 2,120 1,550 1,700 1,110 1,210 860 940 780 850
6 3,180 3,430 2,380 2,570 1,910 2,060 1,360 1,470 1,060 1,140 950 1,030
7 3,770 4,020 2,830 3,020 2,260 2,410 1,620 1,720 1,260 1,340 1,130 1,210
8 4,360 4,630 3,270 3,470 2,620 2,780 1,870 1,980 1,450 1,540 1,310 1,390
9 4,960 5,220 3,720 3,920 2,980 3,130 2,130 2,240 1,650 1,740 1,490 1,570
10 5,560 5,820 4,170 4,370 3,330 3,490 2,380 2,490 1,850 1,940 1,670 1,750
11 6,150 6,420 4,610 4,820 3,690 3,850 2,640 2,750 2,050 2,140 1,850 1,930
12 6,740 7,020 5,050 5,270 4,040 4,210 2,890 3,010 2,250 2,340 2,020 2,110
13 7,340 7,620 5,510 5,720 4,400 4,570 3,150 3,270 2,450 2,540 2,200 2,290
14 7,940 8,220 5,954 6,170 4,760 4,930 3,400 3,520 2,650 2,740 2,380 2,470
15 8,530 8,820 6,400 6,620 5,120 5,290 3,660 3,780 2,840 2,940 2,560 2,650
Source: NEXCO EAST Highway Design Manual, 2005
2) Toll Booth Layout

Figure 9.12-1 shows the toll booth layout for this project.
9-56
Toll Facility
Tunnel Portal
FIGURE 9.12-1 (1) TOLL BOOTH LAYOUT AT WESTSIDE
Tunnel Portal
Toll Facility
FIGURE 9.12-1 (2) TOLL BOOTH LAYOUT AT EASTSIDE
General outline of toll facilities

l 3 lane@3.0m (West Side), 2 lane@3.0m (East side)
l 3 simple booth (West Side), 2 simple booth (East side)
l Information sign & pavement-marking
l Roof
l Lighting
9.13 DISPOSAL AREA DEVELOPMENT PLAN (MICHI-NO EKI1)
9.13.1 Objective
The expected volume from excavation of tunnel is approximately 176,000 m2. The JICA-
assisted Data Collection Survey proposed three locations as candidates for disposing the
excavated soil. It further proposed several method such as, use of space for control office of the
tunnel, to improve existing road alignment at hair-pin curves if required and to provide a
“Michi-no-Eki”.
The objective for the plan of Michi-no-Eki is to promote the road service facility for the safe
1 Michi-No-Eki is a facility developed in Japan, which literally means “road station”, provided on National Highways and
arterial roads for the purpose to integrate parking area, rest rooms (toilets), information facilities and community facilities
provided by local governments.
9-57
driving and comfortable service for road users such as truck, tourist bus and private vehicles,
and contributing tourism promotion and local economy.
9.13.2 Existing Rest Facilities along Tribhuvan Highway
(1) Location of Existing Rest Facilities
The JICA Survey Team carried out the existing rest facilities survey along Tribhuvan Highway
between Naubise and Nagdhunga Pass. Sixteen (16) rest facilities are located as shown in
Figure 9.13-1.
These rest facilities expect No.1 are illegally operated by the private companies. DOR has
ordered to these facilities to move out of ROW of DOR. Car drivers, truck drivers and tourist
buses are using these illegal rest facilities, it is understood that there are high demands for rest
facilities.
(2) Average Distance between Rest Facilities
The average distance between rest facilities is shown in Table 9.13-1. The average distance is
approximately 0.82 km.
Source: JICA Survey Team

FIGURE 9.13-1 LOCATION OF EXISTING REST FACILITIES ALONG TRIBHUVAN
HIGHWAY
TABLE 9.13-1 AVERAGE DISTANCE BETWEEN EXISTING REST FACILITIES
Distance (km)
Location No. Note
between point from base point
Westside 1 0.62 8.80 Legal
from West 2 0.85 8.18 Illegal
Portal
3 0.47 7.33 Illegal
4 0.58 6.86 Illegal
5 0.25 6.28 Illegal
6 0.10 6.03 Illegal
7 0.26 5.93 Illegal
8 2.16 5.67 Illegal
9 0.54 3.51 Illegal
10 2.97 2.97 Illegal
11 0.00 0.00 Illegal
9-58
Distance (km)
Location No. Note
between point from base point
Eastside 12 0.74 0.74 Illegal
from West 13 0.81 1.55 Illegal
Portal
14 0.06 1.61 Illegal
15 0.16 1.77 Illegal
16 1.79 3.56 Check Point (Naagdhunga), Legal
Average 0.82 -
(3) Typical Type of Existing Rest Facilities

The existing rest facilities have various problems as follows;
1) Parking space is provided very close to the existing road and not paved, thus in very bad
condition.
2) Toilets are provided at most rest facilities, however, they are very dirty and unhealthy.
3) Some stores are doing business.
4) There is no stores which sell local products.
Parking space and situation Toilet situation
Multiple shop facilities Shops sells some snacks, drinks and fruits
PHOTO 9.13-1 TYPICAL FACILITIES IN THE AREA
9.13.3 Tourism Spots and Local Products

(1) Tourism Spots
This project provides vital access to the famous tourism spots which are located in Kathmandu,
Pokhara, Chitwan National Park and others. Therefore, this Michi-no-Eki will be utilized by
local and foreign tourists.
1) Kathmandu
Kathmandu tourist sports are Patan area, Bhaktapur area and Thamel area where many tourists
are visiting.
9-59
Patan Area Bhaktapur Area Thamel Area
PHOTO 9.13-2 TOURISM SPORTS IN KATHMANDU
2) Pokhara
Pokhara is very famous lakeside resort in Nepal. Many tourists enjoy trekking in and around
Pokhara.
Source: Source: Source:

http://www.explorehimalaya.com/ http://www.nepallinktravel.com/ http://www.pokharapalacehotel.com/
Lakeside Temple Trekking Mountain
PHOTO 9.13-3 TOURISM SPORTS IN POKHARA
3) Chitwan National Park
This park is located in south central Nepal. Tourist can enjoy safari wildlife tour.
Park Tour Wild Animals

Source: Department of National Parks and Wildlife Conservation
PHOTO 9.13-4 TOURISM SPORTS IN CHITWAN NATIONAL PARK
(2) Local Products in Project Area

Major local products are paddy rice, maize, wheat, tomato and mushroom etc, in project area
and shown in Table 9.13-2. These products are basically provided for their consumption and
are not for sale. Michi-no-Eki can provide opportunities to sell local products and farmers will
bi inspired to produce more to sell products at Michi-no-Eki for their additional income.
9-60
TABLE 9.13-2 LOCAL PRODUCTS
District VCD 2s Major Agricultural Products
Mahadevsthan Paddy Rice, Maize, Wheat, Tomato, Mushroom and Cauliflower
Balambu Paddy Rice, Maize, Wheat and cauliflower
Kathmandu Dahachowk Paddy Rice, Maize, Wheat, Tomato and Mushroom
Thankot Paddy Rice, Maize, Wheat, Tomato and Mushroom
Baad Bhanjyang Paddy Rice, Maize, Wheat, Potato and Tomato
Dhanding Naubise Paddy Rice, Maize, Wheat, Potato, Tomato, Cauliflower and Cabbage
9.13.4 Candidate Locations of Disposal Area and Rest Facilities

Candidate locations of disposal area/rest facilities are shown in Figure 9.13-1.
Alternative-1: Located adjacent to the West Portal of a tunnel, thus excavated material can be
disposed at the cheapest cost. About 150,000 – 200,000 cubic meters of
excavated material can be disposed.
Alternative-2: Located at about 3.00 km away from the West Portal, and about 150,000 –
200,000 cubic meters of excavated material can be disposed.
Alternative-3: Located at about 0.00 km away from the West Portal, and not advantageous as a
disposal area. This site is located near Naubise, thus convenient for people to sell
local products.

FIGURE 9.13-2 PROJECT SITE
9.13.5 Comparing with the Disposal Area

Three candidate locations are compared from the viewpoint of 1) Site Condition, 2) Filling Cost
3) Environment Impact and 4) Impact on Tunnel Project and shown in Table 9.13-3.
2 Village Development Committee: VDC is the lower administrative part of its local development ministry. Each district has
several VDCs, similar to municipalities but with greater public-government interaction and administration.
9-61
TABLE 9.13-3 COMPARISON OF DISPOSAL AREA
Evaluation Item Alternative-1 Alternative-2 Alternative-3
Location
ž This site is located adjacent to West ž This site located at about 3.00 km ž This site located at about 8.00 km
Portal of a Tunnel. away from the West Portal of a away from the West Portal of a
ž About 150,000 – 200,000 cubic Tunnel. Tunnel.
Site Condition meters of excavated material can A ž About 150,000 – 200,000 cubic B ž This site located near Naubise. C
be disposal meters of excavated material can be
disposal
9-62
Landfill is near, cost is cheap. Landfill is middle, Cost is expensive. Landfill is far, Cost is more expensive.
Filling Cost A B C
ž Firm land ž Firm land ž Firm land and residencies

Environment Impact ž Stream B ž Stream B C
ž Transfer length of evacuated ž Transfer length of evacuated ž Transfer length of evacuated

Effect on Tunnel material is shortest for disposal material is 3.00 km away from the material is 3.00 km away from the
area. A West Portal of a Tunnel is high cost. B West Portal of a Tunnel is highest C
Project
cost of alternative.
Total Evaluation Recommendation 1 Not Recommendation 2 Not Recommendation 3
Notes: Evaluation of compatibility, A: Good, B: Tolerable

9.13.6 Layout of Typical Michi-no-Eki
(1) Estimation of Demand of Parking Lots on Michi-no-Eki
The parking area will be arranged in each zones like car, mini bus, large bus and truck, and then
the large truck will be parked at the Michi-no-Eki not to make a traffic jam with other vehicle.
Therefore, estimation of demand of parking lot on Michi-no-Eki is calculated as followings;
1) Calculation Condition
Demand of parking lots is resolved based on 1) target interval of Michi-no-Eki, 2) design daily
volume and 3) utilization factor. In principle, it is calculated by traffic classifications in older to
calculation items are shown in Table 9.13-4.
TABLE 9.13-4 CALCULATION ITEMS
Items Figure Remarks
Target Interval of Roadside Station (L) 10 km
Small Vehicles 4,824
Design Daily Volume (N) Year 2025
Large Vehicles 6,045
Small Vehicles 0.007
Stop Ratio at Michi-no-Eki (S)
Large Vehicles 0.008
Small Vehicles 0.08
Peak Hour Ratio (P)
Large Vehicles 0.08
Small Vehicles 0.25
Parking Occupy Ratio (O)
Large Vehicles 0.20
Source: Design Guidelines of Road (Chubu Regional Development Bureau in Japan, 2014)
2) Calculation for Demand of Parking Spaces

Formulation of demand of parking spaces and calculation formula is shown in below.
N = L (km) x S x P x O (1)
Where,
N – Demand of Parking Spaces
L – Target Interval of Michi-no-Eki
S – Stopping Ratio at Michi-no-Eki,
P – Peak Hour Ratio
O – Parking Occupy Ratio
Target Interval of
Number of Vehicle Number of Vehicle Demand of Parking
Michi-no-Eki
Stop at Michi-no-Eki Stop at Peak Time Spaces
x Design Traffic Volume
Stop Ratio Peak Hour Parking Occupancy Ratio

Ratio
FIGURE 9.13-3 FORMULATION OF DEMAND OF PARKING SPACE
3) Result of Number of Parking Spaces
Result of number of parking spaces at proposed Michi-no-Eki are shown in below,
· Small Vehicles: 7 (nos)
· Large Vehicles: 10 (nos)
Although parking spaces were calculated based on above formula, sufficient land required of
large vehicles parking lots cannot be secured in this area consideration for driveway. Thus,
large vehicles parking lots are planned depending on available land required.
9-63
(2) Infrastructure Plan for Custom Facility
The plan for the infrastructure of the Michi-no-Eki will be designed based on the analysis of
present condition in terms of 1) water supply facility, 2) sewage facility, 3) energy and electric
power facility and 4) communication facility. Table 9.13.6-2 shows the present condition and
plan strategy for the infrastructure plan.
TABLE 9.13-5 PRESENT CONDITION AND PLAN STRATEGY FOR INFRASTRUCTURE
PLAN
Infrastructure Present Condition Plan Strategy
1) Water supply · Water supply facility is not · The facility of water supply will be
facility existing in the project area used, according to constructing
because of disposal area. water tank.
· New deep well in the site will be
developed if necessary.
2) Sewage facility · Sewage disposal system by · The sewage facility and sanitary
discharging to stream. sewage system by septic tank will
· Sanitary sewage disposal system be constructed for public toilet and
by direct stream. restaurant.
3) Energy and · Middle-voltage line on the · The existing high-voltage line in the
electric power mountain site will be used by a lead-in cable
facility · Fire power supply by propane from the Tunnel.
gas and charcoal · The existing system for fire power
supply will be used.
(3) General Layout of Facilities

1) Basic Concept for Facilities at the Michi-no-Eki
General layout of some facilities at the Michi-no-Eki is considered by basic concepts as shown
in below;
· From a hygiene standpoint, the public toilet and the restaurant should be separated
buildings.
· The public toilet and the restaurant will be applied water place, they should be located at
grand floor. And, water tank has to locate between building of toilet and restaurant.
· The septic tank should be constructed in the Michi-no-Eki for sanitary environment.
· The management office and the information center are located restaurant in a corner.
· The trash cans should be located at various places in the Michi-no-Eki.
· The shop facility will be located at 2nd floor within same building of the restaurant, which
will sell some snacks, drinks and local productions.
2) General Layout of Facility
The layout of general and typical facilities is shown in Table 9.13-6 and Figure 9.13-4 to
Figure 9.13-5. A compact style facility will be made an appeal of “Festivity” and “Amenity” to
the road user without felling of pressure, and will be also made an appeal of “Landmark”. The
total area of site will be estimated at 4,650 m2, which is comprised of parking area at 471.5 m2,
plaza area at 442 m2, building area at 329 m2 and green area at 290 m2.
9-64
TABLE 9.13-6 VALUE OF PROPOSED FACILITIES
Items Units Value Contents
Plaza area m2 442 m2 Including pedestrian aisle
Washstand: 3 pieces
Male 32.5 m2 (6.5m x 5.0m) Urinal: 6 pieces
Water closet: 3 pieces
Toilet Washstand: 3 pieces
Female 32.5 m2 (6.5m x 5.0m)
Water closet: 8 pieces
Access Aisle 7.5 m2 (1.5m x 5.0m) -
Total 78 m2 (13.0m x 6.0m) -
Restaurant 154 m2 (11.0m x 14.0m) Table: 9 sets
Wash place, cooking table,
Restaurant (1F) Kitchen 40 m2 (4.0m x 10.0m)
shelf, refrigerator, etc
Total 194 m2 -
Managem
ent Office and
m2 16 m2 (4.0m x 4.0m) Working table, PC, shelf, etc
Information Center
(1F)
Shop (2F) m2 135 m2 (15.0m x 9.0m) Shelf, casher, table
Small and Middle 25 nos (5.0m x 2.3m) -
Parking Large 8 nos (15.0m x 2.3m) -
Total 552.0 m2 -
Green Area m2 290 m2 -
Water tank, septic tank, dump
Others m2 116.25 m2
yard
FIGURE 9.13-4 LAYOUT OF THE MICHI-NO-EKI IN THIS PROJECT
9-65
Toilet
Restaurant, the Information Center and the Management Office
Shop
FIGURE 9.13-5 LAYOUT OF FACILITIES
9-66
9.13.7 Operation and Maintenance for the Michi-no-Eki
Scheme of administrative organization for the Michi-no-Eki and part of O&M is considered as
followings;
1) Based on the new regulation of MoPIT, DOR will be submitted the application document to
MoPIT which are permitted for bidding and sub-contract under DOR.
2) After submission the application document, MoPIT will judge this document and accept for
undertaking the bidding and selection private company under DOR.
3) DOR-PMU will conduct the bidding for private company to operate the rest facility
depending on fair evaluation.
4) Private company will operate and maintain the rest facility (Restaurant, Toilet, Shop). And,
revenue collected from the facility will be used for the O&M of the facility. However,
maintenance of parking space, drive way, information facility and beautification of Michi-
no-Eki will be responsibility of Tunnel Management Office.
5) Tunnel Management Office and private company should tie-up to operate and maintenance
of Michi-no-Eki.
Submission of application document

DOR
Acceptance of document
MoPIT
Bidding and Selection O&M private company

DOR-PMU
Shift the operation
Tunnel Management Tie-up

Private Company
Office
Operation and Maintenance Operation and Maintenance
Rest Facility Rest Facility

l Parking and driveway l Public Toilet
l Beautification of Michi-no-Eki l Restaurant
l Shop
Information Facility
l Road and traffic condition guidance
l Tourist spot guidance
FIGURE 9.13-6 SCHEME OF CONFIGURATION FOR ADMINISTRATIVE

ORGANIZATION FOR THE MICHI-NO-EKI
9.13.8 Project Cost Estimate

The project cost for the construction of the Michi-no-Eki is shown in Table 9.13-7. The project
of a typical the Michi-no-Eki was estimated at 36.3 million Rupees.
TABLE 9.13-7 PROJECT COST ESTIMATE
No. Major Item Cost (Million Rs)
1 Construction Cost 34.5
2 Maintenance Cost (1 year) 1.8
Total 36.3
9-67
9.14 POSSIBILITY OF LOWERING OF GROUNDWATER LEVEL
9.14.1 Climate Conditions in the Study Area

There is a rainfall of about 1400mm per year in Kathmandu. Rainy season and dry season are
clearly separated. During the rainy season between May and September nearly 90% of the
annual precipitation is observed. Precipitation since June of this year follows that of the normal
year.
Source：Department of Hydrology and Meteorology

FIGURE 9.14-1 ANNUAL RAINFALL
Month 1 2 3 4 5 6 7 8 9 10 11 12
precipitation normals (mm) 14.4 18.7 34.2 61.0 123.6 236.3 363.4 330.8 199.8 51.2 8.3 13.2
Mean temperature normals (℃) 10.8 13.0 16.7 19.9 22.2 24.1 24.3 24.3 23.3 20.1 15.7 12.0
Source：Department of Hydrology and Meteorology

FIGURE 9.14-2 MONTHLY RAINFALL
9-68
http://www.dhm.gov.np/uploads/climatic/1002508489Monsoon Monitoring 18july2014.pdf
FIGURE 9.14-3 CUMULATIVE RAINFALL FROM JUNE 1, 2014
9.14.2 Water Usage in the Study Area

(1) Hydrological investigation results
Hydrological investigation was carried out in the end of July. Water quality and quantity are
shown in the APP NO. 11-a of the Preliminary Design Drawing Sheets. Because it was
carried out during the rainy season, the flow rate was higher relatively.
There are many intake pipes from the stream. They have been used as agricultural water and
domestic water. Utilization of many wells has been confirmed in the tunnel route near the top
of the valley.（see NO. 11-b of the Preliminary Design Drawing Sheets）
PH and EC of wells are shown in NO.11-c and NO.11-d of the Preliminary Design Drawing
Sheets respectively.
9-69
Totipakharoad
Balkhukhola
FIGURE 9.14-4 HYDROLOGICAL EXPLORATION RESULTS
9-70
Totipakharoad
Balkhukhola
FIGURE 9.14-5 WATER SOURCE LOCATION MAP
9-71
Totipakharoad
Balkhukhola
FIGURE 9.14-6 WATER QUALITY OF THE WELL (PH)
9-72
Totipakharoad
Totipakharoad
Balkhukhola
Balkhukhola
FIGURE 9.14-7 WATER QUALITY OF THE WELL (EC)

9-73
Balkhukhola
Totipakharoad
FIGURE 9.14-8 GROUNDWATER LEVEL CONTOUR MAP
9-74
(2) Water usage of each basin
Tentatively water basins are divided into 5 locations as is shown in Figure 9.14-9.
C
D
E B
FIGURE 9.14-9 BASIN CLASSIFICATION

1) A area
【Drinking water】
Drinking water is from well water or spring water.
【Agricultural water】
Due to the utilization of water for domestic use in the upstream area, water does not flow
through the streams. Therefore, paddy field is small.
Area panoramic view
2) B area
Drinking water is often from wells until near 100m upstream from the Totipakha Road. In the
higher locations upstream of it, drinking water is from water of stream.
9-75
Tomato cultivation is a thriving place. Tomato cultivation makes use of the water of the stream.
There are a lot of paddy fields, there is a water use of the stream.
【Water use of other】
There is a large pond upstream, it is used as a venue for training fish farm.
House cultivation
Agricultural pond
Paddy
Pipeline
Pond fish farm
3) C area
Residents of this watershed are using spring water or stream. There is information that has
water conveyance from afar.
There is water in the stream, paddies irrigated area is wide.
9-76
Paddy
Area panoramic view
4) D area
They are using the spring water in the upstream of the stream.
Stream water can be seen only after rainfalls. There is a paddy field on the downstream side of
the Totipakha road, They are irrigated with rainfall.
Paddy
Area panoramic view
5) E area
The use of the spring water.
Not farmland.
9-77
9.14.3 Study of Groundwater Lowering Range
(1) Hydrological Method of Takahashi
A rough estimation of groundwater lowering due to tunnel excavation was done by using
Takahashi’s method which is one of Hydrological methods. The catchment area of the tunnel
approximates the shape and size of the basin with the flow path length comparable to the tunnel
length. This method consists of empirical rules. Hydrological method is represented by the
average permeability around the shape of the basin.
Kt＝R２/6H （Kt：Average permeability）
R=A/2Ｌ
R：Average basin width
A：Basin area (m2)
L：Flow pass length (m)
H：Relative elevation difference (m)
9-78
Groundwater level lowering range
Groundwater flow before

the tunnel excavation
(The outflow to the river)
Groundwater table after

Groundwater table before
the tunnel excavation Groundwater flow after
(The outflow in the tunnel)
H-R Curve
FIGURE 9.14-10 CONCEPT OF GROUNDWATER LOWERING RANGE BY
HYDROLOGICAL METHODS
(2) Groundwater lowing range of the tunnel due to hydrological methods
The groundwater lowing range was studied in two representative basin close to the tunnel.
A basin：Kt = 76.2（L=865m A=253,788m2 H=47.1m）
B basin：Kt = 82.1（L=955m A=433,418m2 H=104.5m）
As is shown in the drawing (APP NO. 11-d of Preliminary Design Drawing Sheets
Preliminary Design Drawing Sheets) that area of the groundwater lowering are very wide.
However, the model is a very simplified model and actual geological condition in the area
differs very much from the model. Geological structure is sub-parallel to the tunnel axis and
bedding planes of the strata are sub-vertical dipping north or south due to minor foldings. Strata
consist of alternation of sandstones and slates where slates are generally impervious. Thus
groundwater may infiltrate from the sandstone layers vertically and migration of groundwater in
lateral direction which cut the bedding planes hardly occurs. Moreover, as are shown in the
App. 9c and 9d of the Preliminary Design Drawings, there develop impervious clay layers
which limit the movement of the groundwater surrounding the tunnel. Thus order of lowering of
groundwater level due to tunnel excavation is supposed to be not so large. The matter shall be
further studied in Detail Design Stage because it relates to the manner and quantity of chemical
injection during tunneling which significantly affects the tunnel cost and construction time.
9.14.4 The drought management consideration by groundwater lowering
There is a possibility that the groundwater level is lowered by the tunnel excavation. Therefore,
it may be necessary to consider beforehand about the drought management. There are
permanent measures and emergency measures for drought management.
(1) Measures for drinking water
Water trucks may be used in emergency cases.
As for permanent measures there are several ways;
① Headrace from a nearby stream
→ It is very difficult to design any headrace because there is little water in a nearby stream.
② Development of a new well
→ There is a possibility near Balkhukhola or the opposite bank of the Balkhukhola. It requires
pumping up systems and piping systems to distribute the water to wide spread area where
inhabitants live.
③ Horizontal boring to the mountain
→ It is very difficult to determine where to make drilling as well as it may affect the present
9-79
water use.
The potential is a new well development in the second.
It may be possible to newly develop wells but it should be studied and prepared before
construction starts.
(2) Measures for Agricultural water
Flow rate of the stream is less when there is no rainfall. Therefore, paddy irrigation relies on
rainfall. It is possible that the flow rate of the stream is reduced by the tunnel excavation. But
paddy irrigation may be possible. However, it should be noted that there is a spring water in the
paddy fields of the downstream side of the Totipakharoad.
There is an item of some permanent measures.
① Development of a new well---unrealistic
② Pond Construction---very difficult
③ Crop substitution compensation
④ Compensation in money
⑤ Alternate site compensation
It is necessary to examine the measures in accordance with the situation.
(3) PROPOSAL OF PERIODIC OBSERVATION
Periodic monitoring of wells are necessary during construction in order to grasp the lowering of
groundwater by tunnel excavation. Periodic observations measure water level, flow rate and
water quality. Periodically monitoring points are shown in the APP NO. 11-d of Preliminary
Design Drawing Sheets. Monitoring shall be done for wells at the left bank of the river.
9.15 PROJECT RISKS AND OTHER ISSUES TO BE STUDIED FURTHER
9.15.1 PROJECT RISKS

(1) Construction risks
1) Tunneling is an underground activity where complete geotechnical conditions generally are
not foreseen at the design stage. Moreover, due to the difficulty to carry out seismic
refraction survey and the lack of proper equipment for exploration drilling, condition of
rock mass and distribution of classes of tunnel types may differ from the supposition in our
current design and international design team shall carry out above investigations in their
early stage of detail design to make it clearer.
2) It is anticipated that surface water flows in the valley areas and groundwater level are
lowered by tunneling to some extent. Groundwater being extracted from wells and surface
water are utilized for domestic use and agricultural use and significant shortage of water
may cause serious problem for the implementation of the project. Groundwater monitoring
shall be continued throughout the detail design stage and construction stage and adequate
measures against water shortage when it occurs shall be studied during detail design stage.
3) To minimize construction risks the prequalification of contractors should focus on their
technical capabilities in handling similar works. Especially their experience of tunneling in
difficult ground with employment of particular auxiliary methods shall be carefully
considered.
4) The implementation of the project requires substantial land acquisition and resettlement. On
some recent infrastructure projects in Nepal delays in completing resettlement has led to
delays in project implementation.
9-80
(2) Operation Risks
Characteristics of drivers’ driving manners and vehicle characteristics are as follows;
(a) Drivers try to overtake slow moving vehicles, even using space of an opposite direction
lane. If this kind of driving is practiced inside the tunnel, there is a high risk of fatal traffic
accident.
(b) There are many old trucks and they often stop on the road due to breakdown of vehicle.
Breakdown vehicles are particularly observed at up-grade sections. Currently they stop at a
shoulder or at an emergency bay.
(c) High rate of old model of vehicles causes high rate gas emission which affects visibility and
high contents of CO, NOx, etc. inside a tunnel.
Tunnel cross section and facilities were planned and designed in due consideration of above
drivers’ and vehicles’ characteristics.
During the detailed design, the following should be considered;
1) To cope with (a) and (b) above, study lane width and shoulder width
This Study : Upgrade direction 3.5m + 2.5m (shoulder) = 6.0m

Downgrade direction 3.5m + 0.5m (shoulder) = 4.0m
Possible Alternatives to be studied during the detailed design are;
· To specify 2.5m shoulder as a climbing lane and all trucks shall utilize a climbing lane.
· To widen a climbing lane to 3.0m instead of 2.5m (tunnel cross section is to be widened by
0.5m or use carriageway width of 3.25m).
· To install flexible plastic poles at a center line to avoid vehicle to use the opposite lane.
2) To cope with (c) above, review ventilation system
This Study : In due consideration of present vehicle condition, number of jet fans,
visibility meters, CO meters, etc. were planned.
Detailed Design : Review number of jet fans, etc., carefully in due consideration of
vehicle conditions.
3) To operate a tunnel safely, one of the most important issues is to educate the drivers prior to
opening of a tunnel. Under the Capacity Development Program, the Traffic Safety Campaign
is planned. This campaign should be continuously implemented even after a tunnel opened
to traffic by the Tunnel Management Office.
4) Timely implementation of maintenance work such as pavement markings, cleaning of

lighting facilities, etc., shall be implemented regularly and whenever identified as necessary.
Tolls are collected from tunnel users, thus, Tunnel Management Office must provide high
quality of tunnel facilities.
9.15.2 Important issues to be further studied in DD stage

(1) Prevention of lowering of groundwater level
In the preliminary design of the tunnel chemical injection is designed in type D1-b and D2-a by
utilizing the AGF method for all the surrounding periphery of the tunnel as well as additional
chemical injection from the shotcrete surface where water inflows are observed after
excavation.
However, when the geological condition is taken into account that strikes of the strata are sub-
9-81
parallel to the tunnel axis and dips are generally in high angle to the north or to the south
depending on minor folds, groundwater may perforate into the fissures in the sandstones in
vertical direction and due to the thin alternation of sandstone and shale in which shale is
impervious groundwater may not migrate to lateral direction across the bedding planes.
If this is the case then waterproofing by chemical injection may be OK to be carried out along
the periphery of the tunnel arch instead of along all the periphery of the tunnel. It may reduce
the construction cost and time drastically.
It is strongly recommended to the DD designers to further study on this point after getting
results of seismic refraction survey and drilling surveys. Seismic survey may reveal the depth of
the debris above the rock mass. Some of drilling surveys shall be done in short length in the
rock perpendicular to the tunnel axis to confirm the strikes of the rock to be sub-parallel to
tunnel axis. Thus, adequate hydrological model can be established and proper chemical
injection design can be recommended.
Schematic geologic and hydrologic model is shown in APP. NO. 9-c and 9-d of Preliminary
Design Drawing Sheets.
(2) Ground treatment at the eastern portal area
Chemical injection from the surface is designed at eastern portal area in order to minimize the
lowering of groundwater level here. Along the tunnel and road axis talus deposits distribute
above the weathered rock mass. Groundwater is supposed to be trapped in weathered rock mass
as pressurized groundwater in the area from the drilling result of TC1 which was carried out at
the Data Collection Survey stage. However, in the talus deposit groundwater was hardly
detected during auger drilling survey in portal area, which may imply that talus deposits contain
high amount of very small particles.
It is recommended in DD stage to excavate a pit near the portal to ensure whether talus deposit
is impervious or not and if lower part of talus deposit contains groundwater. If groundwater is
supposed to be accumulated and trapped only in the uppermost weathered part of the rock mass,
then total length of the chemical injection treatment from the surface can be significantly
reduced. The treatment may target the zones from the lower part of talus deposits to weathered
rock mass till 3m coverage of treated zones are obtained beneath the tunnel base.
(3) Review of longitudinal geological profile of the tunnel
Due to the difficulty in carrying out seismic survey, dynamites are strictly controlled by the
army, and lack of adequate equipment for core drilling there are uncertainties in longitudinal
geological profile. Thus in the preliminary design tunnel is designed based on supposition that
rock mass may be somewhat inferior than is seen in outcrops. In DD stage seismic survey shall
be carried out in very early stage and core drilling shall be carried out equipped with adequate
double core tubes to make the longitudinal geological profile more accurate.
(4) Monitoring of groundwater level and preparation of adequate measures for water
shortage
Wells and springs to be monitored during construction stage are shown in APP. NO. 11-d of
Preliminary Design Drawing Sheets. There are 52 numbers of wells and springs in the figure
but only the left bank ones of the Ghate Khola shall be monitored. Groundwater level may be
lowered to some extent during tunneling due to the water inflow from sandstones, however,
owing to the chemical injection accompanied with AGF rate of ingress of groundwater is
deemed to be small and after completion of the tunnel construction groundwater level is
expected to recover to the original level.
However, during monitoring of groundwater level when significant lowering of groundwater
level occurs and it affects domestic water use significantly adequate measures shall be taken to
mitigate the situation. DD designers are recommended to prepare adequate temporary water
supply measures to be adopted in case of significant water shortage occurrence.
9-82
(5) Review of alignment in western portal outlet in view of traffic safety
In the preliminary design road to the western direction is descending by 3.22% in the tunnel till
0+200 followed by about 6.3% from here on to the west and meets a signal location where
relocated existing road intersects with the new road.
For the safety of traffic following two points shall be further studied in DD stage.
First one is traffic safety at signal location. New road including tunnel is of very high graded
road with much better pavement than is now and traffic is supposed to descend the new road in
fairly high speed. However, most of vehicles are of very old ones and most of the drivers has no
experience with signaling it is very doubtful whether vehicles can stop properly at the signal.
This is also the case for vehicles from existing road.
Second one is that in the vicinity of tunnel outlet vehicles from existing road may occasionally
plunge into the new road due to very small descending curve with gradient of 5%.
Due to the short duration for the preliminary study our team only could follow the selected
alignment. Above two issues may not be adequately resolved without shifting the tunnel portal
and alignment to some other location, which requires additional topographical survey and
geological investigations.
(6) Requirement of emergency escape measures
According to Japanese Standards, provision of an evacuation tunnel or escape shelter or similar
measures is mandatory for tunnels longer than 3.0km. The length of Nagdhunga Tunnel is
2.5km and fundamentally does not require such provisions. However, the GON requested the
Survey Team to conduct a study on the evacuation method as considering the present condition
of vehicles and driving manner of Nepal, provision of such facility is inevitable. They said they
became aware of the need after observing such facility in one of the tunnels being constructed
in Japan during the visit study to Japan in August. In addition GON said provision of such
measure also necessitates from the fact that Nagdhunga Tunnel- potentially being the first
highway tunnel in the history of Nepal- will hopefully be a model project for other similar
projects, such measure are desirable to be undertaken. Following the request from the GON, the
Survey Team conducted a study of different methods as shown in Table 9.15-1. The Survey
Team recommended Case-4 and suggests further study in the detailed design stage.
9.15.3 Important issues to Construction stage
(1) Flexible Action for Change Order
Tunnel construction methods highly depend on the geological conditions, accordingly
construction cost varies drastically. Even though detailed geological survey is undertaken, it is
impossible to reveal exact geological condition and it can only be known during construction. It
is also true that it is quite difficult and unrealistic to stop tunneling work during construction
and it should be continued.
In view of above, one of the most important considerations on tunnel construction is that the
Government can approve change order(s) based on the recommendations of the Consultant as
soon as the unexpected geological conditions are found. The contract of tunnel project should
clearly specify the above conditions so that the bidders can be able to bid based on the fare price
without taking account of changes of geological condition.
There will be plus or minus change orders. In anticipation of plus change orders, GON shall
prepare sufficient budget for the Project with the anticipation of change orders. Price
contingency and physical contingency should be included in the annual budget. In case that the
allocated budget for the Project is found to be insufficient, DOR shall realign the budget of
other projects in order for this tunnel project to be continued even under unexpected geological
conditions.
Above these project risks and issues were summarized in Section 17.6 with other risks.
9-83
TABLE 9.15-1 NAGDHUNGA TUNNEL OPTION COMPARISON
Case-2 Case-3 Case-4 Case-5

Case-1
Main Tunnel (Base Plan) Main Tunnel (0.5m Expansion) Main Tunnel (Base Plan) Main Tunnel (Base Plan)
Case Main Tunnel (Base Plan)
+Evacuation Tunnel +Escaping Shelter(W=1.5m) +Escaping Shelter(W=1.2m) +Inclined Escape Adit
(Road Width=0.5m+2.5m+3.5m+3.5m+0.5m)
(Road Width =0.5m+2.5m+3.5m+3.5m+0.5m) (Road Width=2.5m+3.5m+3.5m+0.5m) (Road Width=2.5m+3.5m+3.5m+0.5m) (Road Width=0.5m+2.5m+3.5m+3.5m+0.5m)
Plan
Cross
Section
Ø In case of happening the vehicle trouble, Ø In case of happening the vehicle trouble, Ø In case of happening the vehicle trouble, Ø In case of happening the vehicle trouble, Ø In case of happening the vehicle trouble, emergency
emergency parking bay can be utilized. emergency parking bay can be utilized. emergency parking bay can be utilized. emergency parking bay can be utilized. parking bay can be utilized.
Safety Facilities Ø In case of happening serious traffic accidents like Ø In case of happening serious traffic accidents Ø In case of happening serious traffic accidents like Ø In case of happening serious traffic accidents like fire
Concept fire accident, escape of tunnel users and passing like fire accident, escape of tunnel users is fire accident, escape of tunnel users is possible by accident, escape of tunnel users is possible by utilizing
the evacuation vehicles are possible by utilizing possible by utilizing escaping shelter.(Adult utilizing escaping shelter.( A adult and a child can inclined escape adit.(Evacuation vehicle can not pass)
evacuation tunnel. two people can run in parallel) run in parallel)
Main Tunnel: 89.25m2 Main Tunnel: 89.25m2
Main Tunnel
Cross Sectional Main Tunnel: 89.25m2 Evacuation Tunnel: 19.56m2 Main Tunnel: 95.17m2 Main Tunnel: 89.58m2 Inclined Escape Adit: 19.56m2
Area Total: 108.81m2 Total: 108.81m2
(Base Case) (+19.23m2) or (1.21) (+5.92m2) or (1.07) +0.29m2) or (1.01) (+19.23m2) or (1.21)
Main Tunnel: 10,626 Million JPY Main Tunnel: 12,860 Million JPY Main Tunnel: 10,626 Million JPY Main Tunnel: 10,626 Million JPY
Cost Main Tunnel: 10,626 Million JPY Evacuation Tunnel: 3,349 Million JPY Escaping Shelter: 123 Million JPY Escaping Shelter: 99 Million JPY Inclined Escape Adit: 4,179 Million JPY
(2014 Price)
(Without VAT) Total: 13,975 Million JPY Total: 12,983 Million JPY Total: 10,725 Million JPY Total: 14,805 Million JPY
(Base Case) （3,349 Million JPY）or (1.32) （+2,357 Million JPY） or (1.22) （+99 Million JPY） or (1.01) （4,179 Million JPY）or (1.39)
Construction
43.0 months（Base Case） 43.0 months（+0.0 month） 44.0 months（+1.0 month） 43.0 months（+0.0 month） 43.0 months（+0.0 month）
Period
- No safety measures are yet considered. - Evacuation tunnel L=2.45km, H=3.5m, width=3.5m, 5 - Escaping Shelter width of 1.5m provided. - Minimum Escaping Shelter width of 1.2m provided. - 4 Inclined Escape Adits are provided.
adits 500m interval
- Emergency vehicle for rescue and fire fighting can pass
Other
Evacuation Tunnel.
- In case of another 2-lane tunnel required, Evacuation
Tunnel can be utilized as a part of additional Main Tunnel.
Recommendation Recommended
9-84

Preliminary Design of Tunnel

Uploaded by

Copyright:

Available Formats

Preliminary Design of Tunnel

Uploaded by

Document Information

Original Description:

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Preliminary Design of Tunnel

Uploaded by

Copyright:

Available Formats

CHAPTER 9

PRELIMINARY DESIGN OF TUNNEL

9.1.1 Geological Survey

FIGURE 9.1-1 LOCATION MAP OF GEOLOGICAL SURVEY

TABLE 9.1-1 SURVEYED AMOUNT LIST

FIGURE 9.1-2 GEOLOGICAL MAP OF SURVEYED AREA

FIGURE 9.1-6 INTERPRETATION OF RESULTS OF MAM, ERT AND BORING

9.1.2 Summary of geological survey on Nagdhunga Tunnel

FIGURE 9.1-7 FEATURES OF BEDROCK WITH MANY CRACK

9.2 KEY POINTS FOR TUNNELING FROM THE VIEWPOINTS OF GEOTECHNICAL

9.3.1 Design Standards

TABLE 9.3-2 STANDARD SUPPORT PATTERNS FOR TWO-LANES TRAFFIC TUNNELS

C II-a 1.5 1.2 Upper - - Full

9.4 CROSS SECTION AND SUPPORT PATTERNS OF THE TUNNEL

9.4.1 Tunnel cross section

9.4.3 Longitudinal profile of the tunnel

9.5 METHOD OF TUNNELING

9.5.1 Geology, geotechnical and hydrological condition of the tunnel

FIGURE 9.5-1 ROAD-HEADER AS TUNNELING MACHINE

TABLE 9.5-1 COMPARISON OF EXCAVATION METHOD

Ground is fairly stable, but Alternate excavation of Alternate excavation

Excavation & Mucking Excavation & Mucking

Support System Support System

FIGURE 9.5-2 PROCEDURES OF MICRO BENCH-CUT EXCAVATION

(1) Tunnel excavation and support installation

FIGURE 9.5-4 FLOWCHART OF OBSERVATION AND MEASUREMENT

9.6 AUXILIAR METHODS

FIGURE 9.6-1 LONG SPAN FORE-PILING IN DIFFICULT GROUND

FIGURE 9.6-2 IMAGE OF EXECUTION OF LONG SPAN FORE-PILING

Construction of Portal Portion Excavation of Tunnel Portion

1. Shotcrete for cutting face

Drilling and Injection Work

1. Installation of AFG steel

Restart for Tunnel Excavation

FIGURE 9.6-3 PROCEDURE OF AGF

9.7 DESIGN OF TUNNEL PORTALS

FIGURE 9.7-2 TUNNEL ENTRANCE STRUCTURE

9.7.2 Western portal

FIGURE 9.7-3 TUNNEL ENTRANCE STRUCTURE

9.8 TEMPORARY FACILITIES AND EQUIPMENT NECESSARY FOR TUNNEL

(2) Facilities for the Outside of Tunnel

Control Office-2 (East Portal Side)

Number of Vehicles on Tunnel Section ② （veh/day）

Number of Vehicle on Existing road ③ （veh/day）

Year 2020 2025 2030 2035

(4) Type of Ventilation System

Above 80km/hr 50%

Nagdhunga tunnel 40km/h 100ppm 40%

Big-sized car 5.1 2.3

Longitudinal gradient Altitude (m)

FIGURE 9.9-3 CORRELATION DIAGRAM FOR TRAFFIC VOLUME AND NUMBER OF

Jet Fan Diameter of Fan (mm) 1250

Flow rate (m3/s) More than 43

FIGURE 9.9-4 INSTALLATION OF JET FAN

PHOTO 9.9-1 JET FANS INSIDE TUNNEL

9.9.3 Tunnel Lighting Facilities

Entrance Interior Entranc e

Note Primary Lighting

FIGURE 9.9-5 COMPOSITION OF TUNNEL LIGHTING